American Civil Liberties Union

A private cyber security expert gained access to the e-mail listserv of Occupy Wall Street organizers and forwarded e-mail threads on the planned peaceful protest to the FBI, NYPD, and Comcast.  An FBI agent indicated the Occupy Wall Street protest was an “emerging threat to U.S. information systems” that the FBI was “monitoring and preparing to meet… with physical security.” 

http://gawker.com/5850054/meet-the-guy-who-snitched-on-occupy-wall-street-to-the-fbi-and-nypd