http://news.cnet.com/8301-1009_3-10012612-83.html

LAS VEGAS–A federal judge on Saturday granted the state of Massachusetts’ request for an injunction preventing three MIT students from giving a presentation about hacking smartcards used in the Boston subway system.

The undergraduate students were scheduled to give a presentation Sunday afternoon at the Defcon hacker conference here that they had said would describe “several attacks to completely break the CharlieCard,” an RFID card that the Massachusetts Bay Transportation Authority uses on the Boston T subway line. They also planned to release card-hacking software they had created.

The best part is

..what looked like a black and white faxed copy of the entire presentation was entered as evidence in publicly available court records available on the Web on Saturday, meaning any attempt to limit its distribution further will encounter an additional hurdle.