I just left the Genius bar because the back of my 3GS would rattle when you tap it around the camera lens. The Genius opened the phone and said the lens seemed loose so he gave me a replacement. We did the same tapping around the lens on the new phone and it makes the same rattling noise like something is loose. He said this must be due to the new lens and the way they mount it. Another customer at the store also checked his and the same thing happened. Anybody else notice this? Maybe I'm anal but it does bother me a little bit. Not enough to get rid of the phone though.