I also wonder what this means for Padilla - a US citizen. what I see in this law is what I would have given to Padilla, he can challenge his status as a combatant, but once its clear that a fair process has made that determination - he belongs to the military after that. However, if they are giving that to non US persons, I imagine Padilla will (sadly) get a biger bite of the apple.
Padilla is a different story. I think if you're arrested on American soil, and you're an American, you must be given all your Constitutional rights, even if you've been actively treasonous. But those SOBs in Guantanamo should have been summarily shot after interrogation. Or save the bullets and shove `em out the back of a C-47 afterward. Either way, it's as fair as they deserve for fighting a war by hiding among civilians.