Setting aside the truly ludicrous idea that imprisoned terrorists are going to break out of prison like something out of an old Jimmy Cagney movie, I have heard from a number of readers who say we should be worried that these terrorist prisoners will spread their ideas within the prison system. If you imagine that these al Qaida dudes are going to be hanging around the prison yard, pumping iron and forming their own Islamist gang to go toe to toe with the Aryan Brotherhood and the Black Guerrilla Family that might make some sense. But I don't think these folks are really familiar with how the federal supermax facilities work these days -- particularly the premier one in Florence, Colorado, where all the high profile baddies are. All these guys are in solitary lockdown at least 23 hours a day, when they're allowed into a special exercise cage. Then there's the 78 cell "control unit" for prisoners who are not allowed any contact with anyone. This article from the Post from a few years ago has more details.