Agile Messenger the feature rich and user friendly all-in-one MSN®, AIM®, Yahoo!®, ICQ® & GoogleTalk® instant messaging client for the iPhone that we saw first for V1.x is now officially available via the AppStore in iTunes.
AgileMessenger allows you to send instant text and picture messages to anyone on your MSN®, AIM®, Yahoo!®, ICQ® & GoogleTalk® contact list directly from your iPhone.
Save money on SMS: Agile Messenger sends all messages through your data-plan, there is no per message charge! Works with iPhone and iPod Touch. Costs $9.99 (Expensive!)
Update: Agile messenger has been updated for OS 3.0 with push notifications. Thats amazing!