We have had IM+ on our iPhone for way long, but we have been using Fring till now. Since the 2.0 update released on the app store, this app has been given a pretty cool UI. All stability issues have been solved. » App Update Review: IM+ v2.0

BeejiveIM is a new iPhone/iPod Touch chat application that has been released in the App Store. BeejiveIM supports almost all known IM networks like MSN/Windows Live, Yahoo, Google Talk, MySpace, ICQ, Jabber and AIM/Mobile Me. The features that BeejiveIM has are extensive:
» BeejiveIM chat client with MSN/Live and ICQ support – App Store

MobileChat ,yes the jailbroken app of Twenty08 has made the jump to the App Store. Many of our first gen iPhone readers will know this app from the Jailbreak community. This was always one of my favorite applications that i installed on about any iPhone. Today it has been released in the App Store. Although it’s not free like PalRingo, it’s still worth while if you don’t like palringo very much.
» App Store – MobileChat moves to the App Store

AgileMessenger is a new native iPhone chat application from AgileMobile that is just fantastic. AgileMessenger supports nearly any chat application like ICQ, MSN, AOL, Yahoo!, Jabber and GoogleTalk). The list of functions is almost limitless.
» AgileMessenger – iPhone messenger client (AgileMobile)