"A federal judge ordered three college students to cancel a Sunday presentation at a computer hackers' conference where they planned to show security flaws in the automated fare system used by Boston's subway.

The temporary restraining order, issued by a U.S. district judge in Massachusetts, prevented the Massachusetts Institute of Technology students from demonstrating at the Defcon conference in Las Vegas how to use the vulnerabilities to get free rides."

http://news.yahoo.com/s/ap/20080810/ap_on_hi_te/subway_hack