Slashdot is reporting that TorrentBits.org and SuprNova.org have gone dark. There seems to be little really solid news as to the reason, but widespread speculation is some kind of crackdown on illegal copying.
When more details are available, I will likely have more to say about it, but for now I merely point out that BitTorrent relies on centralization, and as such is easily targetted both by the legal system as well as computer forensics. If you choose to illegally trade files on BitTorrent, you are on thin ice in both regards.
If you are a P2P developer, you should probably read Fred von Lohman's piece so as to educate and arm yourself.