The downside is that you're trusting your Google Voice and Twitter logins to third-party services, but if you wanna get push notifications about @mentions or DMs from Twitter or SMS messages from Google Voice without keeping a computer running at home with Growl whenever you're out, they're the way to go.

Any other services that use Prowl this way? [GVMax, Prey Fetcher, Thanks Zachary!]

Well, push describes a lot of things. Push is simply an action. Versus, say, pulling. Maybe that's horribly abstract, so try this: If information shows up on your phone or neural implant or messaging program without you (or your wares) asking for it—that's push. The info is pushed to you, versus you pulling it from the source. There are tons of ways push can be (and is) used.

Email's a pretty good starting point for grasping the difference between push and the other stuff. You probably know good ol' POP3—you log into your mail server and pull down new messages. Maybe it's on a frequent schedule, so it feels automatic, even instant, but you're still reaching out to the mail server every time to check and see if there's new mail to download.

IMAP is a little fancier than POP, where all of your folders and email are the same on all of your computers, phones and other gadgets, and any change you make on one shows up on the other, since it's all happening on a remote server somewhere. But with the standard setup, it's still the same deal—your mail program has to log in, see what's new, and pull it down. IMAP does have a pretty neat trick though, an optional feature called IMAP IDLE, that does push pretty well—it's what the Palm Pre uses for Gmail, for instance. Essentially, with IMAP IDLE, the mail server can tell whatever mail app that you've got new messages waiting, without you (or your app) hammering the refresh button over and over. When the app knows there's new messages, it connects and pulls them down, so it gives you just about the speed of push, without matching the precise mechanism.

While different systems do things differently (obvs), what true push services have in common is that they generally insert a middleman between you and the information source.

RIM's setup for the BlackBerry is probably the most sophisticated. When your BlackBerry registers with the carrier (which has to support BlackBerry), the details are handed to RIM's network operating center, so the NOC knows where to send your mail. The NOC watches your mail server, keeps tabs on the phone's location, and pushes email through to your phone whenever you get new stuff.

What makes it push is that your phone's not actually polling a server for new messages to pull—it only receives them when they hit your inbox, and are then pushed to your phone by RIM's servers. This means you save a lot of battery life that'd be wasted by making the phone constantly hit the servers for updates. The flipside is that when RIM's servers blow up, you don't get email, since it's all routed through their system—hence the other panic that grips dudes in suits once every few months lately.

The other biggie is Microsoft, who has Direct Push, part of Exchange's ActiveSync. It's architected a little bit differently, so it doesn't need the precise kind of data about where your phone is that RIM's NOCs do: The phone or whatever you've got sends an HTTPS with a long lifespan to the Exchange server—if new mail arrives before it dies, the Exchange tells your device there's new stuff, so it should start a sync. After it syncs, the device sends out another long HTTPS request, starting it all over again.

Apple's weak-sauce substitute for multitasking works pretty similarly: The developer has something its wants to send an iPhone, when its application isn't actually running, like an IM. It sends the notification to Apple's push servers, which send the notification to the phone through a "persistent IP connection" the phone maintains with the servers. This connection, which is only maintained when push notifications are turned on, is needed to locate the phone, but still doesn't draw as much power as constantly pinging the mail server.

Of course, those aren't the only push systems around, and it's only getting more and more important as stuff gets shifted to the cloud. We haven't mentioned Android and Google Chrome, but both utilize push (or will) in different ways. Suffice it to say, Google Sync will soon be a major player in this game. But basically, all kinds of different data can be pushed—calendars, contacts, browser data, hell, even IM is a kind of push—and they all work more or less the same broad way. Just don't ask us why there isn't push Gmail on the iPhone yet.

Still something you wanna know? Send questions about pushing, shoving and pancake massacres to tips@gizmodo.com, with "Giz Explains" in the subject line.

Just found a HUGE #security #hole w/ push & AIM. Someone got my sent messages and wrote back. DO NOT send confidential AIM msg to #iPhone

#iPhone #push #security #hole:my msg was received by an hacked iPhone w/ push service hack; msg seems to be broadcasted to all hacked phones

Take extreme caution when sending AIM msg to people w/ hacked iPhones. Push service broadcasts your msg to strangers. Pls RT

@martinhering there seems to be a brand new hack that reactivates push with the effect that received msg are broadcasted to strangers

Here's a screenshot the random receiver of my msgs sent me back http://twitpic.com/b3bct I used iChat on a Mac #iPhone #push #security #hole

The problem seems a result from a hack to avoid Apple's jailbroken/unlocked iPhone push blockade, so if you haven't used any of this, keep sending your kinky messages to your mistress or master as usual. Otherwise, zip it.

Update: Yes, it's confirmed. The problems are a result of the patch to fix the push blockade. [Twitter via CrunchGear]

iTweetReply is a full-blown regular Twitter app for $2, though it's not the prettiest or most feature-packed—except for the push notifications for mentions and direct messages. Boxcar, on the other hand, works with the Twitter app you already use—when you get a push notification of a mention or DM, it'll open your favorite Twitter app. Interestingly, it costs more than iTweetReply, at $2.99.

Since DMs go to me as text messages, I don't need push enough rightthissecond to shell out another $3 on top of the money I've already shelled out Twitter apps. They'll get around to it. [iTweetReply (iTunes), Boxcar - Thanks Marsala]

It's dead simple—you enter your Gmail account information and that's it. On the backend, it's actually using Gmail's standard IMAP idle function (but on the developer Tiverias' servers), so there's a slight delay between the mail hitting your inbox and the notification getting pushed from them to your phone. But the 10-30 seconds lag MG Seigler reports is totally acceptable, especially since you get a pop-up preview of the email.

Two things: Seigler doesn't make it clear if it supports more than one Gmail account, and all those pop-ups could get annoying, if you get a ton of email, anyway.

Oh, and it's possible Apple won't let it into the App Store. They say none of their code violates Apple or Google's ToS, but as Seigler points out, we all know how "reasonable" the App Store review process is. But even if it is blocked, all hope isn't lost—you can pull a similar workaround using the $2.99 Prowl app, which pushes Growl notifications from your Mac (and soon, Windows PC) to your phone, so you can be pinged whenever you have new messages that way.

I have to say, I'm loving seeing push notifications used for more excellent purposes than just IM apps. [TechCrunch]

The possibilities really are endless: You can be pinged with a push notification when a torrent finishes downloading, you get a new IM or email, you're mentioned on Twitter, or anything else Growl can notify you about.

You can customize which notifications are pushed to your phone and when they're sent (like only if you're not at your Mac), and Prowl stores up to 30 days of them. Way awesome, since it effectively makes iPhone push notifications infinitely extensible. Update: Ooo, support for Growl for Windows is coming soon too (thanks Samsita!). [iTunes, Prowl via Daring Fireball]

It certainly isn't the most creative use of background notifications—the messages only pop up when you're challenged by another player—and I'm already wondering how, when all kinds of apps have this capability, the iPhone's exceedingly simple notification system will scale.

OS 3.0 users can give the free app a try now, but keep in mind that we'll probably see more than a few push-equipped apps rolling out in the next few days, as I'd imagine Apple will want to have a few high-profile 3.0-capable downloads available at launch. Alternatively, if downloading the app, getting a friend to download the app, and having him challenge you to a Lady GaGa tap-off is a little too embarrassing for you, just watch the video below. —Thanks, Tim G! [Video from 9to5Mac]

The image associated with this post is best viewed using a browser.

The Pronto shares the same $20 monthly plan as the original Peek, but on top of unlimited push emailing, that plan also supports unlimited text messaging. The Pronto's software is also a bit more advanced, including the ability to check out documents and PDFs, as opposed to just pictures.

The Pronto is available now, but unlike the original, it's only in black (they call it gray). [Peek]

UPDATE: Over on the Peek messageboards, one user claims that the old Peek will receive the same software soon. Consider that unconfirmed, but it seems likely enough.

UPDATE 2: Future Peek Classics will no longer have SMS.

Faster syncing with Mac and PC. Changes you make to contacts and calendars on your Mac (Address Book and iCal) or PC (Microsoft Outlook) are now automatically pushed up to the cloud every time you make an update. Likewise, changes you make on me.com, iPhone, or iPod touch are automatically pushed to your Mac or PC. As a result, your contacts and calendars update faster across all your devices. To take advantage of faster syncing, be sure you're running Mac OS X Leopard 10.5.6 (Mac) or MobileMe Control Panel 1.3 (Windows).

After a lousy launch in 2008, Apple decided to avoid associating the word "push" with Mobile Me until they could get synchronization between computers and mobile devices (iPhones, iPod touch) down to acceptable times. Looks like it's close enough now to bring the term back.

Another new feature, iDisk file sharing, has been around since the 13th. Improved iPhone notification and syncing and better web app performance round out the improvements.

Dear MobileMe member:

Over the past few months, we have been working hard to make MobileMe the best service it can be. Here is a summary of the improvements and performance enhancements that have recently been completed.
Easy file sharing. iDisk now makes it even easier to share files that are too big to email. Simply select a file in the iDisk web app and click the Share File button to generate an email with a download link. You can also optionally add password protection and set an expiration date for the link. For more details, view this tutorial.

Faster syncing with Mac and PC. Changes you make to contacts and calendars on your Mac (Address Book and iCal) or PC (Microsoft Outlook) are now automatically pushed up to the cloud every time you make an update. Likewise, changes you make on me.com, iPhone, or iPod touch are automatically pushed to your Mac or PC. As a result, your contacts and calendars update faster across all your devices. To take advantage of faster syncing, be sure you're running Mac OS X Leopard 10.5.6 (Mac) or MobileMe Control Panel 1.3 (Windows).

Improved notifications and sync on iPhone. Reliability of new email notifications and syncing of contacts and calendar with MobileMe have both been improved. To get the best MobileMe experience on your iPhone or iPod touch, you should be running iPhone Software 2.2 or later.

Better web app performance. We have also improved the overall performance of the web apps at me.com including faster start time in Calendar and searching in Contacts. For more details, see this support article.
Remember, to take advantage of these improvements, your computers and devices must be running the latest software versions indicated above.

All of this was possible before through a smartphone's web browser (and Google Sync has been available on Blackberries for months), but if you were looking to push update your phone to various Google-stored information through the iPhone or Windows Mobile, it was pretty much a read-only experience. Now you can treat Google's calendar and contacts like any push service, updating your phone to the cloud in real time.

And I'm way too excited about this development. [Google Sync via lifehacker]

UPDATE: I'd mentioned that Gmail was included. It is not.

Android and especially the Pre have made background apps and the true multitasking they allow look a lot sexier, and the iPhone's one-app-at-a-time paradigm more restrictive, even with the innovative compromise of push notifications.

Push notifications, for the uninitiated, would allow apps like AIM to send you notifications (through Apple) of say, new IMs via an SMS-like prompt, even while the application isn't running. So you could kind of think of the app as running in the cloud, essentially. Not multitasking by any means, but for some an acceptable compromise on battery-draining background apps.

MacRumors says that if what they're hearing is true, and Apple allows apps to run in the background, it would happen with the iPhone 3.0 software. On the current iPhones, it would likely be restricted to one or two processes at a time, but with the beefier hardware of the next-gen iPhone, it'd be less restricted.

Having apps actually run in the background might actually be worth the longer wait. [MacRumors]

The latest iPhone 2.2 operating system fixes many things, but something is still missing: Push notification services. Once again, Apple has missed the opportunity to enable push notification in a new update, which is specially bad after they failed to meet their self-imposed September deadline. That makes it almost two months late now. So what's the problem? Is the cause just a technical glitch or maybe there are other hidden, last-minute reasons behind it?

Many developers and users were eagerly awaiting for the 2.2 update to finally enable push notification services, which disappeared from the 2.1 beta right before release. Essentially, push notification is a clever way for your iPhone applications to receive messages from the network at all times, even while they are not active. Since the applications don't need to be active constantly, asking data to the application server every X minutes, this method saves power while giving you all the convenience of server-sided push messages.

As any BlackBerry user knows, push services allow the developer to implement functionality that is extremely useful. For example: An instant messenger program would be able to notify you whenever a new message is received, even while the application itself is not running. Think about it just like an SMS. Another example: A voice over IP application can receive a call and alert you right away, so you can pick it up like any normal telephone call. Or maybe return the call using the normal telephony service if you are not in a Wi-Fi spot.

As you can imagine, this makes push notification a Holy Grail for users and developers alike. The only people who may not be happy about these are the carriers. After all, the idea of an instant messaging application with push notification services taking over their lucrative SMS business doesn't seem like a very good one.

Or maybe I should take off my tin foil hat and just assume that Apple has hit a roadblock that nobody at engineering ever expected. But a two month delay? Why? It just sounds too weird.

Whatever it is, I only hope they deliver it as soon as possible.

After buying the iPhone I remembered that I could get annoyed every five seconds with its built-in push mail. I checked the preferences and I saw Push was turned on. Then I waited.

I waited. And waited. And then waited some more. But nothing arrived. Push wasn't working.

In fact, according to reports in support forums, the whole thing is not working well yet. But what's not working at all is the Push Notification services that Apple promised to developers. Apple has yet to put these online, so third-party applications can receive information from the network in the background, in real time, without having to waste battery life or processor power pooling the servers every few minutes.

Apple was supposed to have the Push Notification service in place in September, but September has passed and there is no fix in sight. Hopefully it will come out soon because, for businesses, developers, and people addicted to instant-everything, at this point the iPhone is not the solution they were looking for.

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Until now, the only thing that separated the BlackBerry from the iPhone—apart from the iPhone's better, faster and more powerful operating system—was the push email on the BlackBerry. (Well, and the physical keyboard that some people say they could never part with.) I was a CrackBerry addict myself before getting the iPhone, and the only thing I missed (sometimes not really, because it can get very annoying) was the push email.

With iPhone OS 2.0 and MobileMe (or the enterprise connectivity options) the push email difference is completely gone.

The push mail works flawlessly. Even over international connections: to do the cellphone network test I used a Vodafone Spain SIM card running on the Vodafone UK network here in London. Not a single glitch—the thing just worked almost instantly. Knowing that Apple is using Sun Java Messaging Servers, probably paired with Synchronica or Consilient's over-the-air synchronization modules, I'm not surprised. It feels like they have put together a rock-solid operation.

If you couple that with the fact that both consumers and enterprise iPhone users are going to be able to push sync everything, including calendars, address book and web bookmarks, you can see why Research In Motion is going to have a very tough time defending against the Apple juggernaut on software features. The combination of multimedia, consumer and enterprise features on the iPhone, coupled with the flawless Application Store and its user interface, makes any BlackBerry look like a useless brick.

UPDATE: While we love the push email, Ars has some tests that show why the iPhone may not be ready for primetime enterprise.

AT&T will charge you 15 cents a minute for doing PTT, which you can then convert to a real phone call to save on PTT minutes. Other features like availability status (like IM status), call-me alerts, contact alerts, and quick group calling are also available. – Jason Chen

Press Release [Cingular via Mobile Tech Review]

Even nicer is the Push technology they've thrown on here: Push-to-share sends your dumb friends your even dumber photos and Push-to-talk keeps one lucky person always within the reach of your sharp talons.

This slightly upgraded SLVR should be in stores sometime before the end of the year. For what wireless carrier, um, we don't know, but considering it's GSM, you can probably rule out Verizon Wireless. Hopefully the cellphone performs better than its silly name would lead you to believe. – Nicholas Deleon

new MOTOSLVR L7e handset [Slashphone.com]