Worked like a charm for me - iBook 800 / OS X 10.3.9 / iTunes 5.0 (34) / Adium 0.84

I'm using it for my online status, and including it in my info.

You can do more than just artist and track...
Artist: %_artist
Song: %_track
Album: %_album
My Rating: %_rating
Genre: %_genre
Year: %_year

There might be more - that's all I've found.