Legit Reviews came across a video that allegedly compares a prototype of the iPhone 5 to the current iPhone 4S. While we don't know for certain if it's the real thing, the device looks a lot like the leaked photos that are circulating the web lately. The new device has a longer screen, which appears to be a 16:9 ratio, but not as large as the Samsung Galaxy S3. Other changes include the front facing camera moved from the left side of the speak to above, and the audio jack moved from the top of the phone to the bottom. The dock connector is also different, it's much smaller than the iPhone 4's and it's not backwards compatible:
Apparently, Apple isn't too happy about the plethora of third party docks that have sprung up around the iPod and iPhone, so they have designed this new connector so that only approved third party docks can be made. There is actually a special chip behind this connector which will perform an encrypted handshake with an equivalent chip in the third party dock to ensure compliance. This is Apple's usual control-freakery shining through once more. Be prepared to throw out your existing docks and spend big on new versions, with potentially more limited choices.