In p2p sharing networks the latest weapon the file sharers are deploying is encryption. Sure encryption has been around for years but it seems the file sharers are now using the technology coupled with services like BitTorrent.
According to The Register, a large UK ISP says the number of encrypted files being shared has risen tenfold in the last 12 months. Obviously this is nothing to sneeze at.
As the article points out, files which are encrypted draw more attention and law enforcement agencies spend more time on these files than more theoretically innocuous ones.
As always happens in these electronic espionage wars, one side finds a new weapon and the other responds with something else more sophisticated. The record labels have found their business has turned more into a Spy vs. Spy cartoon than the good old business of making CDs and selling them at Tower Records.