Supposedly on GameSpot's forums, his dad or some relative worked at Microsoft, and probably worked in the Xbox department. When that whole ordeal came up, the Xbox 360 was only in it's alpha stages. The Beta XDK's hadn't been delivered to developers yet. Also, even if he was a tester, why is there nothing but that pillow? I've seen other pictures taken at other angles, and the room (which looks like an apartment room) is pretty much empty. I think that's a prototype model, which doesn't work, because the XDK's that were delivered to developers were in black and came with a power unit attached to the top.
This is what the Xbox 360 XDK's looked like: