In this blog post, Brian Ross of ABC News reports that:
"The FBI acknowledged late Monday that it is increasingly seeking reporters’ phone records in leak investigations. “It used to be very hard and complicated to do this, but it no longer is in the Bush administration,” said a senior federal official."
According to Ross:
"Officials say the FBI makes extensive use of a new provision of the Patriot Act which allows agents to seek information with what are called National Security Letters (NSL). The NSLs are a version of an administrative subpoena and are not signed by a judge. Under the law, a phone company receiving a NSL for phone records must provide them and may not divulge to the customer that the records have been given to the government."