Ok, I'm sure this is not news to anyone, but I made the mistake of buying a $6.99 silicone case at Marshal's for my new 3GS black iphone. I've only had it 3 weeks and the bottom bezel is scratched, and there are several light scratches on the back of the phone... Might as well just kept it naked in my pocket.
I ordered a new iskin solo fx case, hopefully I have better luck with that one!