I just recently got my first iPhone 4 replaced because of the proximity sensor. It was running iOS 4.1 and the problem was confirmed at the Apple store. I got a replacement for it that is showing the exact same problem. I can't stand being on a call and suddenly wondering why the other person can't hear me (because my cheek hit mute). Is anyone still having problems after updating?? I'm definitely holding the phone up against my ear (which worked fine on my 3GS). Is it possible that this is a hardware problem on both phones or am I just dumb and doing something wrong? I'd just like to hear your opinions before I go back for another replacement. Oh yeah one more thing, when is Apple going to fix the green spot that shows up in pictures? And the horrible white balance under artificial lights? That should be easily fixed in software, or they could at least provide a manual override.