Facebook is the modern AOL. (How? In more bad ways than one actually, but for now.... One conglomeration of rubes ruined the beginning of the internet experience, the other is ruining the end.)
Only this fact could make me "thankful" that it's "only" Twitter getting more integration.
Sheeple are sheeple. Enjoy!
(FWIW, I did participate a little bit in Ping as I could see some value in a music-focused service like that. Not good enough for the Facebook'ites apparently....oh well.)
Hey dude definitely, they might add it and but it won't substitute it as .Mac still performs. It's even in my signature.
They could probably do something similar to Last.fm, which scrobbles the songs you listen to and then based on that finds you recommendations of new bands/artists and friends with a similar taste to you.