There is an interesting paper from the 2012 P2PSecComm get together.
A system to track and identify a bit torrent user in less than 3 hours:
The paper is called “The Unbearable Lightness of Monitoring: Direct Monitoring in BitTorrent”
It can be found here:
http://www.cs.bham.ac.uk/~tpc/Papers/P2PSecComm2012.pdf
