iResQ, the iPhone/iPod repair site, has posted pics of what they claim is the front faceplate of the next-gen iPhone. Two things about this piece of hardware are particularly interesting. First, the part is approximately 1/4 of an inch taller than the iPhone 3GS, indicative of a slightly taller form factor for the next-gen iPhone. Second, there's a small, reflective strip directly above the hole for the phone speaker. iResQ believes this is likely to be the new location for the iPhone's proximity sensor rather than an indication of any new hardware; however, moving the proximity sensor to a new location and increasing the overall length of the device could still point to a front-facing camera or other new hardware on the next-gen iPhone.
It's worth mentioning the possibility that these "iPhone" parts aren't legitimate. iResQ hasn't revealed its source for the part, and purported iPhone bezels leaked in 2009 turned out to be parts for a completely different device. The backside of the supposed next-gen iPhone's face is missing quite a few parts present on the iPhone 3G and iPhone 3GS, which either means the part iResQ received was incomplete, the next-gen iPhone has had its internal hardware shifted around, or the part is fake.
So case manufacturers, don't throw out your old blueprints just yet. Unfortunately, it's likely we won't find out whether these are legit or not until June/July of this year; despite rumors of an iPhone update in April, the most likely date for the next-gen iPhone's release is early summer.