My first MacBook (Late 2006, 2GHz C2D, SuperDrive) had an issue with discoloration, even though it had supposedly been fixed by then.
I think the main issue now is build quality. My second MacBook (replaced the first, Mid 2007, 2.16GHz C2D, SuperDrive) had the casing come apart and the battery start to bulge.
For $1400 after taxes, you'd think Apple would be able to build notebooks as sturdy as sub-$1000 PCs.