I have tested MAC Authentication on WiNG v4.3.3 with ADP5131 v2.5.2 against Windows 2003 Server (IAS/AD), with no issues. The stand-alone version of the AP5131 does not support MAC Authentication.

Yes, WiNG 4.x supports MAC authentication. No client configuration is necessary, however please note that MAC authentication does not provide for automatic delivery of encryption keys, so use of a PSK is advisable. Setup: WLAN: Set authentication mode to MAC Authentication. Configure RADIUS server IP and shared secret. That's all that needs to be done on the Motorola backbone. On the RADIUS box, you will need to setup user entries consisting of having both the username and password being the MAC address. You can configure how the address is formatted (aa-bb-cc-dd-ee-ff vs aa:bb:cc:dd:ee:ff etc) in the WLAN configuration of the controller. With this enabled, when a device associates, the controller will attempt to authenticate the MAC against the RADIUS server configured in the WLAN configuration. Last I checked, however, this feature was not supported on AAP deployments. Someone from the BU or ECRT may want to advise if that is still the case.