[larrywallace]

Dude, it is the mac address they grab.

I ran ifconfig en1 | grep ether and the mac address showed up on my URL omnibar when I firebugged it.

I've even noticed this happening at Starbucks whenever you use their WiFi - they will sniff your MAC address and it shows up in the URL omnibar when you agree to the WiFi terms.

Will the real hackers please chime in on how this (grabbing MAC address) can be achieved...

[iancarroll]

Yes, this happens at Starbucks because your MAC address is captured when you connect to their wifi network (this happens on virtually any captive portal, not hard). I, for one, cannot find my MAC address in a long list of history because it is simply not passed via web requests.

You can get the MAC address of anyone who is connected to the same network - but that's it.