Please remember that with, say, a macbook, one can easily monitor traffic between your access points and authorized clients of your wireless network. From that

Please remember that with, say, a macbook, one can easily monitor traffic between your access points and authorized clients of your wireless network. From that, is simple to extract the mac address of an authorized client, configure your macbook wireless card with that mac address and join your unencrypted network. This is why mac filtering is useless on wifi networks.