If these are the actual images, the iPhone 5 doesn't really look that much different from the iPhone 4S. It does appear elongated compared to the iPhone 4S, but aside from that, it looks very similar. We're not sure this is the way Apple would go; there was a lot of anger over the iterative nature of the iPhone 4S vs. the iPhone 4, and this would be just another iterative change.
Images showing comparisons of the thickness of the phones show that the iPhone 5 is only slightly - very slightly - thinner than the iPhone 4S. Of course, it is significantly slimmer than the older iPhone 3GS, as is the iPhone 4S.
The iPhone 5 is expected to sport an elongated 4-inch screen, with a new 16:9 aspect ratio that enables Apple to keep the device thinner, side-to-side. It's expected to support 4G LTE, have a slightly larger battery, a moved headset jack, a centered FaceTime camera, and a faster processor. It's unclear if it will support NFC or not.
The launch event is expected to be held on Sept. 12, though it has not been announced yet. The device is expected to ship on the following Friday, Sept. 21, with iOS 6 launching to older devices during the intervening timeframe.