As above reply to kamelion, I'm sure I read it somewhere when I swapped my Be supplied router for my old trusted Netgear DG834GT- and I know that I have the MAC address inserted there
Bob
BT Home Highway+CIX -> Nildram until Pipex -> SKY -> Be*UnlimitedWRBRIX using DG834GT
I think what spoofing the MAC address does is to speed up the connection process (when switching to a different router) - without it, apparently it can take up to 30 minutes the first time. It's mainly used to help ensure that you're assigned the same sticky (but dynamic) IP address. I think!