Yep, I didn't see XM Radio Mobile mentioned anywhere so it was a nice surprise.
There is also a music ID service called MusicID:
Ever want to know what song you're hearing?
Now you can with MusicID from AT&T. From hip hop to country, rock, classical, show tunes and more, MusicID can identify thousands of recorded songs.
When you hear a song, just dial #43.
Hold your AT&T phone up to the speaker for about 15 seconds, then end the call.
You'll soon receive a text message telling you the name of the song.
Neat but don't know how often I would use it:
MusicID | AT&T wireless services