Two chat bots, Alice and Jabberwacky, converse with each other. "J: Yes. Would you like to hear a joke? / A: Sure, tell me about it. / J: Why don't blind people skydive? / A: Perhaps it is impossible. / J: I think you lie a lot." (thx, nick)
Update: Rex Sorgatz ran a similar experiment back in 2002.
Update: Interviews with Robots is an entire blog dedicated to chatbot conversations.
Here's how to connect to Google's IM network with iChat or Adium. The audio works with iChat as well. Not as good as a Google Talk client for OS X, but I guess it'll have to do.
Download Squad has screenshots and a quick review of Google Talk, Google's new IM/VoIP app. Doesn't look Web-based, which is surprising to me. Looks Windows-only as well, which is lame, lame, lame. Update: the Google Talk site appears to be live and letting people d/l the app.