I have a 16GB black 3g that has a rattle too. I did recently drop mine, but it was only a few feet onto carpet and it's in a case. I never really shook it previously so I don't know if it was there before the fall. Also it only seems to rattle when shaken in the vertical axis, not the horizontal axis and while it's hard to localize it seems to come from the bottom half of the iPhone. I asked a "Genius" about it today and he said he didn't think it was normal but since everything was working fine just to keep a close eye out for any dysfunction. Should I ask them to replace it?