Seems pretty normal wear and tear. You'll read many posts from the apple crowd about this. Such as http://arstechnica.com/journals/apple.ars/2006/6/12/4297
It's cosmetic so it doesn't affect use.
is there a way to get rid of them?
I've tried a normal eraser (one used for pencils)
fabric stain remover (I'm desperate)
it seems to appear where I rest my hands on my laptop...anyone else having this problem?