I'm thinking of developing some features for Geekbench and the Geekbench Browser that would require some way of keeping track of which results come from the same computer. One way would be to include some sort of unique identifier (say the computer's MAC address) with each submission to the Geekbench Browser.
What sort of privacy concerns would this bring up? Would people object to having their MAC address sent to a central server? Would you object to it?