There are some very good paid instant messaging apps for the App Store, and plenty of free options too. Meebo is the first that manages to be both, with almost no compromise.
Meebo was one of the first companies out of the gates with an instant message web app for the iPhone, so it's weird that it took them this long to go native. But hey, whatever, they did, and it's goddamn fantastic. Here's the cream of the feature list:
• Multiprotocol support, including obvious choices like AIM, Google Talk, Facebook and MySpace, as well as an impressive list of smaller networks
• Push notifications, which automatically activate when you close the app without signing out.
• conversation logging, not just on your phone, but on Meebo's servers, as associated with your Meebo account.
• "Now typing" notifications, away messages, message copying, landscape mode, swiping between chats—the kind of stuff that makes the experience rich, versus merely acceptable
Meebo's aesthetic is subdued and unobtrusive, and gesture and navigation behaviors make sense throughout the app. Patchy EDGE connectivity didn't seem to degrade my experience at all, push notifications worked like a charm, with roughly two seconds of delay versus a regular client.
In short, Meebo does everything I need from a chat client, does it well, and does it for free. My only hangups? There's no Skype messaging support, and—though I haven't—some iPhone 3G users are experiencing crashes during regular use. But! (And I can't say this enough!) It's free. Just give it a try. Even if you've already paid for a Trillian or a BeeJive, you might find something you like here. [Meebo]