I mine both on deepbit and slush's. When I try to mine using TOR looks like all the connections to deepbit are closed by the TOR nodes; this thing does not happen when I try to connect to slush's. I guess it is a settings in some TOR nodes I pass through, kind of "close all connections to deepbit"!
I also have another rig somewhere else and it mines fine on deepbit, so I don't think they changed anything.