Typing on it is ok because it takes a fair amount of force to push it down.
I'm going to keep an eye on this and probably email Applecare to see what they say about it. I reckon I might send it back if it continues to get worse - as a few days ago it only wobbled a bit, now it's very obvious. As I say, it doesn't affect typing, but it sure is annoying to look at!
EDIT: Yeh, just emailed Applecare. Will whack out my sister's MacBook aswell to see if her's is doing the same. I'm getting so annoyed at Apple now. Tempted to just get my money back and wait a while... Apple... please make me happy!
EDIT 2: Ok, I just got my sister's new MacBook out and tried it on the same surfaces as mine. Now I find that mine is actually flush on some surfaces and not on others. I thought, hey, lets switch batterys... And found mine was suddenly a lot better. Then I took the battery out. It's flush! I think what the problem is, is that the front left where the battery is can be a little lower than the other corners thus giving the appearance of a bend because it's a bit higher. I dunno... it's odd... I'm gonna watch and see what happens