MacRumors has a forum thread about a reader who just bought a used MacBook Air on eBay:
I recently picked up a used Macbook Air 1.6 The bottom case is black without any markings on it. Computer does boot up, but the battery has swollen and distorted the case. I removed the bottom of the case and pulled the battery with thoughts of purchasing a replacement battery. When looking at the connections they are different from the disassembly pictures on the web, and then most of the other internals are slightly different than on the various disassembly sites as well.
Throughout the thread, the owner updates with a few more facts, including the lack of the media function keys, the keyboard backlight, and the “MacBook Air” badge on the bezel. The unit’s logic board is red (it’s a dark green-blue in real life MacBook Airs), and the machine is running 10.4. The real MacBook Air shipped with 10.5.2.
There’s been some debate today about whether this is really a prototype, or a knock-off from China. I vote for prototype. Apple builds their machines and tests them internally, and those machines have leaked out in the past into the hands of regular users.
When I was in Cupertino, I saw a prototype MacBook Pro built inside a large acrylic case. The easiest way to explain the machine is that it was built in an “exploded view” so each part could be seen, and all the connectors could be easily reached. It was pretty cool, but it wasn’t anywhere near what the finished product would be. It used the old-style round power adapter, and did not have an iSight. It booted and ran, but was far from complete. I assume what that guy bought is a more evolved version of the prototype versions of the Air. I wonder what he’ll do with it.