A user claims to have gotten a 'different' iPhone 4 as a replacement. The notable differences include: - a visible proximity sensor (I can't see it on mine, no matter the angle. not to say it's not there, just not apparent) - different shade of black on the front bezel - a more 'matte' look/finish to the antenna side-band, which could indicate coating of some sort The user claims to not have encountered any further issues with this phone, which could indicate that it is a revised modification of the phone. Source: http://gizmodo.com/5586256/ EDIT: Some people who have just recently gotten their iPhone 4's (as replacements or otherwise) are reporting different serial numbers from the usual. Perhaps these are further indications as to a new, possibly fixed revision of the phone?