Are you getting an IP address?
The most common problem with wireless not communicating is a mismatch in security settings, with the common one being the key isn't right. Make sure the encryption of the router/access point match the client (ps3) EXACTLY.
For example - WPA-PSK/TKIP, WPA2-PSK/AES, etc. If you're still having trouble remove the security of the router and see if it works without encryption.
If you ARE getting an IP address then all security/encryption is good and we need to move up the OSI model.