I would guess you need to figure out who actually makes the wifi card in the PS3 and then call the manufacturer for the drivers...From what I've read, there is no kernel support for the PS3's wifi adaptor. Until such a driver exists, there's no way it will connect. An external USB wifi adapter apparently works, but that kind of defeats the purpose...just hang on, I'm sure it's on the edge of happening. At least I'm hoping...
The people at Terra Software Solutions are working with Sony to create a working WiFi driver for the PlayStation 3. You'll just need to wait until they release it.