I just got back from the costa mesa apple store. My new iphone was so yellow I hated it. So, I made a genius appointment online. They acted like they never heard of the problem, but after hemming and hawing, he did open a box and let me see another, which was much better, and they did exchange it for me. Considering all the business I have given them over the years, they sure can be rude, but the outcome was good. It's not as white as my G2, but it's much better.
I dont like the Genius's at the costa mesa store, they act like its a problem all the time and act like they've never heard of the problems everyone talks about. Irvine store, though smaller have some pretty rad staff and genius's there.