According to this story at CNet, unknown attackers have been flooding popular BT networks since last Wednesday, putting servers and tracker hosts to its knees. As some of you know, despite of the fact BitTorrent infrastructure does not depend on a central server for finding/searching through available files on the network (like the old Napster, Kazaa do), it still does heavily rely on trackers that redirect the user to the different pieces of a file which could be hosted on several users' PCs. At the time of posting both Suprnova.org and LokiTorrent sites were down.
"The distributed denial-of-service (DDoS) attack on the BitTorrent infrastructure prevented some users from downloading files for up to 10 hours on Wednesday, said the administrator, who asked to be identified only by his online handle, "Lowkee." The target was the central BitTorrent directories, or trackers, which are used by people to find movies, music and other content on the file-swapping network, he said."
As a side note, Suprnova owners seem to be working on a new file-sharing application called "Exeem", currently under beta testing:
"No more web mirrors, no more bottle necks and no more slow downs. Exeem will marry the best features of a decentralized network, the easy searchability of an indexing server and the swarming powers of the BitTorrent network into one program."