I was shown this by a colleague - interesting debate about the methods used by copyright enforcement agencies (primarily in the US) to issue a DMCA (Digital Millennium Copyright Act (United States)) take down notice to stop the download of copyright materials.
Challenges and Directions for Monitoring P2p File Sharing Networks (PDF) (Also labeled "Why My Printer Received a DMCA Takedown Notice"
by Michael Piatek, Tadayoshi Kohno, Arvind Krishnamurthy
Dept. of Computer Science and Engineering, Univ. ofWashington
Worth a read.
EDIT: Reported on NZ Herald Website as well here by Pat Pilcher