There is no scratch remover for the ALUMINUM
yes... they are actually aluminum and YES there are pieces of the casing that are plastic, but the actual thin outer shell of these things is indeed aluminum (also why they dissipate heat better then the normal macbooks: note I said dissipate, not stay cooler overall, just less of a hot spot. Also why the wifi range is better on macbooks than macbook pros as well)
Anyway. There is no scratch remover sadly.
I had an old powerbook that I took to the hardware/hobby store though and matched the color to a metal dust paint compound (it was like paint but with metal dust in it to help with the color i guess) in the paint isle though... and I took a teeny tiny dab of that and put it "in" the scratch and then QUICKLY wiped the excess off (so the paint basically filled in the scratch).
A lot of old car parts had anodized aluminum type finishes, so there may be car body paint that matches fairly well too.
You have to be careful to not get it elsewhere, but it actually worked quite well after it dried. You could still tell there was a line/scratch there, but it was a lot less noticeable then it was before.
edit: I suppose you could try the silver nailpolish route too. Probably less likely to last, but probably pretty darn harmless to try. It's pretty good at filling in cracks and is easily removed later with acetone which doesn't seem to do any damage to aluminum.
Just a thought.
Either way, any option will be "filling in" the scratches, not really removing or making them completely invisible.