“Undercover operations, long practiced by the F.B.I., have become a mainstay of counterterrorism, and they have changed in response to the post-9/11 focus on prevention. “Prior to 9/11 it would be very unusual for the F.B.I. to present a crime opportunity that wasn’t in the scope of the activities that a person was already involved in,” said Mike German of the American Civil Liberties Union, a lawyer and former F.B.I. agent who infiltrated white supremacist groups. An alleged drug dealer would be set up to sell drugs to an undercover agent, an arms trafficker to sell weapons. That still happens routinely, but less so in counterterrorism, and for good reason.”
“Typically, the stings initially target suspects for pure speech — comments to an informer outside a mosque, angry postings on Web sites, e-mails with radicals overseas — then woo them into relationships with informers, who are often convicted felons working in exchange for leniency, or with F.B.I. agents posing as members of Al Qaeda or other groups.”
This is from the New York Times a main steam news paper too – obviously it’s become an ‘open practice’.