I've had my space gray MBP since launch day and so far there has been no discernible wear or scuffing on the palm rests (where the most friction typically occurs).
I did clumsily drop the computer (while it was closed) on tile from about four feet, and you can see the exposed silver on a corner where it's dented. But the scratch/dent needs to be very deep, as I can only see space gray along the "spine" of the computer on the other end where it was scratched.