Since Apple doesn't release detailed sales information for the iPhone App Store, this figure is just an approximation. LSVP is saying that Apple got about $45 million in total iPhone App Store sales for the last three quarters vs total sales of $25 billion. TechCrunch is saying $95 million, which is the number we have used for our illustration. Obviously, third-party iPhone apps are going to be less costly to sell, with no cost of manufacturing or design.

Still, the difference in total sales is staggering and the profit picture won't be significantly different from this. The chart really gives a good idea on how incredibly tiny the app sales are compared to the company total business. [Based on data from LSVP TechCrunch via Mashable]

The first thing you'll notice about these efforts—coming from such traditionally competitive companies as Palm, BlackBerry, Nokia and Microsoft—is just how similar they all sound. App World? App Catalog? App Market? Mobile Marketplace? This outward likeness actually runs pretty deep—these stores are advertising uncannily similar feature sets, for both users and developers:

Although it might not evident in the feature-by-feature breakdown above, there are two distinct kinds of app store: The primary store, which is the first and only source of an OS's apps (see Apple), and the secondary store, which is built around an existing stock of third-party apps, and with preexisting developers in mind (see BlackBerry, Microsoft, and Nokia). It's a combination of these different lineages and divergent policy choices that make the smartphone app store experience so varied.

Apple's iPhone App Store
At least for now, the App Store is the standard by which all others are judged. Beyond that, it's given us a rough guide for what works. With a $99 dollar developer's fee and a novice-friendly SDK, the barriers of entry for an iPhone developer are fairly low. Distribution, payments and to a large extent marketing are managed by iTunes, which iPhone owners are necessarily familiar and comfortable with.

And, of course, there's the iPhone: This store may only serve one handset (and its very similar nonphone brother), but it's a wildly popular one. This makes the app store uniquely attractive to developers, because it provides access to the largest uniform app-buying market in the world. Microsoft can argue that Windows Mobile 6.5 will connect developers to x gajillion different customers through y zillion different handsets, but this variety is a curse: Handsets have different resolutions, processors, 3D hardware, input types and basic feature sets. A motion-sensing 3D game with a GPS social networking feature won't work on a lot of WinMo handsets, but a 2D, keypad-controlled Asteroids clone won't make a developer rich.

But the App Store is far from perfect. Apple, like all App Store owners, has the final say in what gets listed, delisted or banned, and they aren't afraid to remind us of this. Along with the typical risque/racist/infringing content prohibitions, Apple enforces strict and often limiting rules against apps that compete with the iPhone's native set—iTunes, Mail.app, Safari to name a few—and apps that their partnered carriers aren't too fond of, i.e video streaming and tethering apps. Now, all these rules are showing signs of loosening with OS 3.0, but as long as the App Store is the sole source of iPhone apps, any rules will seem like too many rules—especially if you're accustomed to a totally unregulated system like Windows Mobile 6.1's. Hence, the gray market.

Android App Market
This second major entrant into the app store race represents a consciously different approach than Apple's, but not in that many ways. Immediately, we see a lot to compare: A single-handset userbase (at least for now), low costs for developers and a presence as the primary—though not sole—source of apps from Day One.

But the App Market is a different breed than the App Store. Most importantly, it's not the only place you can get apps. Google has been much more lenient about what they allow in their store since the beginning but in the rare case that they don't approve of an app, as in the case of tethering apps earlier this month, you can just go download an .APK file and sideload it onto your G1 anyway. This is a healthy middle ground for everyone involved; Google doesn't alienate users by destroying entire categories of apps, but isn't forced to come into conflict with carriers because of overly liberal policies. Google has also made their Market more friendly to consumers, with a no-questions 24-hour return policy.

Great! Then why is the App Market so underwhelming? Well, the G1 wasn't exactly a runaway hit, and the store got off to a slow start. Paid apps weren't made available for months after launch, and when they arrived they didn't benefit from the convenience and familiarity of a storefront like iTunes. Moreover, there's no guarantee that things will change that much in the coming months—more handsets from more manufacturers will boost Android's user numbers, but will lead to the WinMo-style toxic fragmentation that Apple so adamantly avoids.

BlackBerry App World
Matt took a dive into the newest mobile app store, and found it agreeable, but not spectacular. RIM's is the beginning of this "secondary" app store concept, and it shows: You'll be hard-pressed to find anything here that wasn't previously available elsewhere. It is simply an aggregator for existing applications.

This was a given, as developers have been cranking out BlackBerry apps for years now. But App World was a great opportunity for RIM to give the lethargic dev community a shot in the arm. Instead of doing that, they've made the store almost hostile to would-be app writers.

Listing your wares in App World costs a hefty $200, which gives you the right to upload 10 apps, but doesn't come with any new SDKs or development tools. The payment system is PayPal, which is clumsy to use and a pain to set up. A minimum non-free price tier of $2.99, probably intended to filter out spammy apps and cover PayPal's transaction fees, discourages developers from even trying to make simple, useful apps, eliminating the $.99-to-$1.99 sweet spot that has been central to Apple's success. App World feels like an afterthought, and a reluctant one. UPDATE: It should be noted that the 70% dev revenue share figure in the chart is incorrect, and has been update to 80%—a marked advantage over the other stores.

Windows Mobile Marketplace
With Windows Mobile 6.5, Microsoft will introduce the Windows Mobile Marketplace. So far, their announcements have shown an awareness of the pitfalls of both Apple's and RIM's approaches: They're emphasizing non-exclusivity and app approval transparency, a 24-hour return policy and wide device support, but also making sure to get big-name app and game developers on board to ensure that users actually have something new to look forward to at launch.

On the developer side, it's a mixed bag. As in every other store, the dev take-home is 70% of each sale, but the listing fees aren't great. $99 gets you five apps a year, but anything beyond that will cost an additional $99. I'm sure this will help vaccinate the Marketplace against the fart app epidemic that Apple has proven so prone to, but it'll do so at the expense of potentially useful free and $0.99 apps—again, a crucial price range. One important factor that's still TBD is the payment system. Microsoft says they'll support both credit card payments and carrier charges, but hasn't yet said how that'll look. In both cases the process will need to be as seamless as possible.

Nokia Ovi Store
You probably haven't heard much about this store, set to debut within a month, but it's kind of a big deal for the 40m+ Symbian S40 and S60 users that it'll serve apps to. It's planned to shoehorn into Nokia's new Ovi app suite, which we were introduced to with the XpressMusic 5800, and provide a go-to source for not just apps, but ringtones, wallpapers, and basically everything else that you might have found in a 2001 vintage carrier WAP store.

There has been a decided lack of fanfare surrounding this launch, probably because there just aren't that many Nokia smartphones in the US. But its success or failure will be informative: It will be the most open of all the app stores. For the time being, there is no developer fee, and app listings are free and unlimited. You can easily publish tons of different kinds of content—Flash Lite apps, Java apps, Native S60 apps, multimedia uploads and others—which will be subject to a vetting process that Nokia has assured will be minimal. As Nokia-averse Americans, we can view the Ovi Store as an experiment in laissez-faire app-mongering—a multi-handset, mixed-media, unfiltered feed of Symbian content.

Palm App Catalog
And finally, we have Palm's App catalog. This is the store we know the least about, but that is already set for a different course than all the others. At launch, the only handset it'll serve will be the Pre—though Palm has indicated that other WebOS handsets are inevitable. It'll be the first—and likely exclusive—source of WebOS apps, and developers will be furnished with a solid, though fundamentally limited, SDK.

Palm's still-vague plan for the App Catalog will no doubt be central to the success or failure of the Pre, but we can make an educated guess at what to expect, assuming that Palm doesn't get taken over by idiots in the next couple months: Palm will vet the apps thoroughly, provide an in-house payment system, and make development simple and cheap (previewed Mojo SDK apps have shown great promise). The end result will probably look something like the iPhone App Store, but with one huge difference: there will be no local natively running apps—the Mojo SDK doesn't provide for that, just for what amount to turbocharged, locally-stored web apps. Granted, these web apps will have privileged access to some of WebOS's core functions, but it's doubtful that high-end gaming, as we've seen on the iPhone, will even be possible on the platform. These limitations (along with WebOS's multitasking advantages) will affect the nature and quality of the apps that are listed in the store much more than the Catalog's policies, though exactly how, we'll have to wait and see.

Still something you still wanna know? Send any questions about app stores, SDKs or the finest in fart-app technology to tips@gizmodo.com, with "Giz Explains" in the subject line.

The Apple submission feedback person says that it violates Section 3.3.12 of the iPhone SDK Agreement, specifically where it says:

Applications must not contain any obscene, pornographic, offensive or defamatory content or materials of any kind (text, graphics, images, photographs, etc.), or other content or materials that in Apple's reasonable judgement may be found objectionable by iPhone or iPod touch users.

We wouldn't say randomly displaying statements about Chuck Norris, which have been all over the net for half a decade now, qualifies as "defamatory content." But then again, we're not on the approval committee for Apple. Nor, are we fans of Chuck Norris jokes. Our parents might still be though, so who is Apple to deprive our parents of corny joke enjoyment?

There's supposedly some unwritten rule among app developers that you're not supposed to use the phone's vibration feature for anything but alerts, not game enhancements. That's right. No force feedback when your race car hits a wall or when your avatar takes a blow to the face. Seems quite arbitrary to us, seeing as most people should be able to figure out that a vibration in a game comes from the game itself, not from an SMS message that didn't also pop up a visual notification.

The second was from another developer who didn't follow Apple's design conventions and put a toolbar at the top of the screen instead of the bottom (yeah, notice how all your apps have the toolbar at the bottom?). Not only that, they didn't change the shade or color or icon of any of the entries on the toolbar to allow the user to see which one was selected, which is a bad design decision if we've ever seen one. Not too bad that this one's rejected.

We're sure there are a few more unwritten rules of iPhone development that we don't know about, so if you're a developer that's been rejected for some reason, drop us a note at tips@gizmodo.com. [TUAW]

Update: Jonathan points out that the force feedback rule could be to avoid paying the patent on rumbling controllers that all the major console makers had to dish out on. Most recently (and notably) seen on Sony's PS3.

The App Store works great on the iPhone 2.0. Fast. Beautiful interface. Simple. It's localized, so you will require an account from the iTunes country you are accessing from (my Spanish iTunes account didn't allow me to download things from the App Store in the UK).

I'm installing the AIM client now. Doing video. Keep checking back.

6:28EST

The installation was flawless. The icon appears on your iPhone screen instantly and you can see a progress mini-bar showing how much is left. Over wireless, AIM for iPhone installed in a few seconds. Another video coming up now.

6:38EST
The navigation is very easy. The whole mechanism is more straightforward than Installer.app. You just use the store to buy things and the updates are presented on a dedicated screen. At the beginning I looked for a place to uninstall applications but nothing was there. The answer is simple: just go into the iPhone home screen, hold an icon for a few seconds and the X to delete the application will appear, just like when you add a web page to the homescreen.

6:47EST
Apparently some readers are reporting that some applications are not available in certain countries in the iTunes App store. I've yet to find this problem in the iPhone App Store, though. If you want me to try any apps, let me know.

7:04EST
I'm downloading applications left, right and center, including the new iTunes Remote application.

7:16EST

The search engine does it by keywords, apparently. New video on all the sections coming in a few minutes.

7:35EST
Here's how you uninstall any application on the iPhone. It couldn't be more simple.

7:39EST
Going to buy an app now. Probably Monkey Ball, but ping me with tips in AIM if you think something is better.

7:50EST
Second part of the walkthrough.

8:13EST
I've downloaded Monkey Ball but it's not working on my iPhone classic. Going to back it up to iTunes. Video of this coming up now.

The backup process started automatically as soon as I connected it, but it's taking a long time to complete.

8:52EST
Sorry for the delay, but I've been playing with the iPhone remote control and other apps. This is just too much fun. Feels like Xmas money. The quality of some of these applications is just amazing. A post on the purchasing process, which works exactly as the free stuff, one-click and install, is coming up in few minutes.

9:29EST
Here's a brief clip on the purchase of Monkey Ball. Very simple as I said, one click. It took ages to install because apparently it is really big.

Stay tuned for the Remote hand-on.

10:39EST
The remote hands-on is live here.