FlickIM, Web Based iChat Client for Your iPhone
Psst...hey, buddy. Over here. So, you want to chat with your friends using AIM or iChat, on your iPhone? Well I got something for you. There's this place on the internets called FlickIM. Just point your browser (via iPhone) to flickIM.com. You punch in your AIM ID, they look the other way, and you send instant messages to your "associates". No questions asked.
I said no questions!