In Windows, it is possible to obtain the MAC address of the wireless access point you're connected to. This is handy when you have multiple access points with the same ESSID (i.e. "roaming") and want to know which one you're connected to. This is done with the netsh CLI tool, available since Windows XP.

To do this, start a command prompt, and type in:

netsh wlan show interfaces

This shows all wireless interfaces on your system. When your wireless is active and connected to an AP, you get output similar to this:

Name : Wireless Network Connection   ...