In Mac 10.5, ichat 4.0 has some nerdy fun new features. I'm not sure if the AIM supports these directly and ichat is just enabling them or if they are ichat-proprietary. Either way, it's great. I don't use all the wacky ichat features - audio, video, screen sharing - yet.
Finally! And they work very well. There are vertical "tabs" on a left sidebar. To enable you have to go to ichat preferences, messages, and check "Collect chats into a single window." it rules.
by going invisible, you can see the status of your friends, but they can't see you and you can still send and receive messages. It's like a more aggressive "Away" status.
Oh yeah, I found a super minor "bug" too - ichat menubar icon missing 'invisible' status.
/me status messages
This only works when both parties are using ichat, but if you type
/me something it sends a IRC-like status message. The best way to understand is to try it. I first read about it at tuaw.com
Async Message Handling
I'm not sure how this really works, but it appears that if you are offline and someone sends you a message, the next time you log in, you will get old messages that were sent while you were away (just like cell phone SMS). Yahoo IM has had this for long time.
Anyone got any details on this? Or is this just the sender resending the message. Either way, it's a good addition
Invoking Applescript on Messages
Ok I haven't tried this, but you can now invoke applescript in response to messages. So you could "auto-accept" new chats. Even better, if everything is set up correctly, you can make a "poor man's remote control" for your computer.