Believe it or not, there are some embedded devices which don't have the CPU juice for WPA2, so they were given a BIOS update so they can run something better than WEP as some form of security. WPA has its issues, but it sure beats WEP.
The best wireless setup is to have two wireless SSIDs. Your internal one that runs off of WPA2-Enterprise, RADIUS server, and smart cards. Then an external one that has a stern packet filter and throttling mechanism. This way, people can log on your open wireless to check E-mail, but Limewire and other P2P apps will be stopped. Of course, someone can jump that, but if they do that, its not your problem anymore.
I do see one use for MAC address security, and its more of a legal thing than computer protection. If a security breach criminal case winds up in court, and you can prove a potential intruder was bypassing your MAC security, it might land a conviction. Otherwise, someone can make up a story of you allowing people to have your WPA2 passwords, etc.