I've heard almost nothing about build quality issues w/ the MBPs.
I bought a black MB (C2D 2Ghz) this last April....it went back a week later b/c the display bezel started to separate. The replacement machine started to squeak/creak/crack when opening/closing the lid. Two visits to the Apple Store later, it still creaked until I demanded a replacement.
The top-case on the third MB (2.16Ghz) started to separate from the machine (pictures here
). I was told this was normal, except they could not explain why it did not exist on a single one of their floor models. That said, I'm not all that impressed w/ the build quality of Apple's latest offerings and this machine is going back.
On the other hand, my fiance bought a refurbished white MB from Apple directly and it's been perfect in every way.