Hey, I don't know where you guys learned about MAC addies, but they're hard-wired into your NIC last I checked - every different NIC has a diff MAC addy.
Hence, it is traceable - but unfeasible over the large internet. However, in a Class C network, you could probably be found. (Class C? 255.255.x.x? I think. I don't quite remember. It's been a while since that class.)
Anyway, you shouldn't spoof you MAC addy - because your card physically won't accept, as in, you can't write your little 'hacks' to overwrite this type thing, any data for a MAC addy other than it's own.