The Department of Homeland Security recently took time to investigate the Phatbot worm which uses technology similar to what P2P networks like Kazaa and Gnutella use. The worm creates networks of computers to send spam and it seeks passwords.
Craig Schmugar of Network Associates says this worm has potential by the way it spreads but considers it "low risk" because not as many computers have been infected compared to other worms like MyDoom.
Joe Stewart of LURHQ Corporation adds, "It's got extra features that make it a little bit more formidable, but it's certainly not a quantum leap in bot technology." It only assembles networks of 50 computers while other worms amass more PCs. Source