I've had this problem before, and i was able to connect by turning the PS3 off and back on. That might help. If that doesnt work, the only thing i could think of to try is to turn he PS3 off and reset your modem. Havent gotten that far but that might help.
For the record, i've been having trouble just seeing games played in matchmaking. It keeps saying there are no games. (On a saturday night? Yeah right) I think theres a problem with the servers tonight.