Actually, you can get in a lot of trouble for sharing copyrighted music, it's just that no one's been taken to court yet. A couple people were nailed for it a few years ago but that was the days of MP3 sites. No users have been sued yet for P2P.

That could certainly change. The maximum penalty for copyright infringement is $150,000 per song infringed, and you could be sued by labels *and* publishers (who represent different copyrights), so double that amount.

More on this at:
http://www.musicunited.org