There is no MAC address when the phone is operating on 3G. The vzw 3g network uses MEID and IMSI. You only have a MAC address when you are connected to WiFi. I totally understand where you're coming from though in asking the question. I looked into it myself because obviously with the use of RDP apps and such you need to open some firewall ports on your PC and setup port forwarding on your router, and that doesn't sit well when you look at your firewall logs and there are hundreds of hits from Asia and South America. Being that you can't get a static IP on a Droid, the next thought is to allow only the MAC address of your droid in and block everything else. It'd be nice if they came up with a pseudo MAC address standard to solve this problem. Smartphones are at the point where they are basically mobile PC's so I think it would make sense to do that.