Via Coolfer comes this story about the Finnish company Viralg who are posting corrupted music files to p2p networks in order to inhibit illegal downloads: http://www.slyck.com/news.php?story=750
As Coolfer says, "the cat-and-mouse game just got more interesting." Labels have trying to seed the networks with dummy files for awhile now, but this is a new step for them and they say that it seems to be working.