From the NYT:

Groups promoting extremist brands of Islam have gained a foothold in American prisons, and counterterrorism officials believe Al Qaeda are likely to try to use the prisons "to radicalize and recruit inmates," according to a Justice Department investigation...

A classified addendum to the report details cases in which counterterrorism officials assert that people leading prison prayer sessions - including authorized chaplains, volunteers and inmates - may have ties to terrorist groups.

In a briefing Tuesday for Congressional officials, the inspector general's office said it found evidence that volunteers leading prayer services had been linked to people who showed up on terrorist watch lists, and that people associated with Al Qaeda had already managed to recruit support within the federal prisons, said Senator Charles E. Schumer, Democrat of New York.

Federal prison officials "were putting out the welcome mat to any group that wanted to infiltrate the prisons," Mr. Schumer said. "There was virtually no vetting of who would become a chaplain or a volunteer, and there was virtually no supervision. It was an invitation to danger..."

There are a few more links in my post from a couple days ago.