It looks like iChat AV is scriptable (at last!). One easy application for this is to set your status message dynamically, to say, the song you are listening to in iTunes. That script would look something like this:
on idle tell application "iTunes" if player state is playing then set a to artist of current track if a is "" then set a to "mysterious unknown music" end if else set a to "nothing" end if end tell tell application "iChat" set status message to "listening to " & a end tell return 20 end idleSave this in script editor as application with "Stay Open" enabled. Have fun!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030707090734302