I finally found a good jabber "client"; for my iPhone: JiveTalk

It's webapp as I didn't find the time to jailbreak my iPhone so far… but JiveTalk is doing a pretty damn good job so far! It heavily relies on anychronous JavaScript (Buzzword: Ajax ;D)

Check out the screenshots


p.s. in case jivetalk doesn't work, there still is meebo which doesn't do all the nice grouping stuff, but works too :)