"In a paper presented earlier this week at the Usenix Workshop on Large-Scale Exploits and Emergent Threats, the researchers demonstrated how they used the technique to continuously spy on BitTorrent users for 103 days. They collected 148 million IP addresses and identified 2 billion copies of downloads, many of them copyrighted.
The researchers, from the French National Institute for Research in Computer Science and Control, also identified the IP addresses where much of the content originated. They discovered the the vast majority of the material on BitTorrent started with a relatively small number of individuals." http://www.theregister.co.uk/2010/04/30/bittorrent_continuous_spying
So why are they trying to sue the millions instead of getting the few that upload the stuff that those millions want without paying ?