The New York Times (reg. req.) reports on a new study from AT&T Labs that found that most films that make it onto filesharing networks came from film industry insiders (Hollywood Faces Online Piracy, but It Looks Like an Inside Job). Unsurprisingly, DeCSS has little to do with movie filesharing. LawMeme took a good look at film bootlegs well over a year ago (The LawMeme Guide to Spider-Man and Star Wars Bootlegs).
UPDATE 1515 ET
Furdlog found the link to the study (Analysis of Security Vulnerabilities in the Movie Production and Distribution Process [PDF]).