While it has always been known that Apple considered a variety of ideas when they were deciding to enter the mobile phone market (with ex employees discussing it behind closed doors, as seen in this Cult Of Mac article, not much was known about alternate versions of the iPhone until now.
Much like the first production iPhone, the prototype features many of the same features including an aluminium chassis, multi-touch compatible screen, 2G connectivity and WiFi radios. However, despite carrying a similar design, the phone itself is extremely different from the iPhone we know today.
Check out the video below to see the so-called Acorn OS at work. Fascinating.