Have you tried putting the PS3 in the DMZ of the router?
Tried disabling the Firewall in the router?
DMZ is Demilitarized Zone, basically it means the PS3 will bypass the firewall while the other computers will still be behind the firewall.sorry i dont understand DMZ?
never had an issue with the wireless on my ps3
as mentioned above check your mac filtering
I think it's more a router problem as I never had real problems with two different SMC routersIts no way user error here or mac filtering its sony!