From Mac OS X Hints.com -
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:
OS version: OS X
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 idle