The iPhone 3G prototypes are rare, and you see (much) more often the first model than its 3G evolution. In this YouTube video, you can see several.
The first one doesn’t even have a motherboard; it comes from a recycling company. Apparently, the finish of the case is not the same as the commercial model. The second one, with its stickers, was broken during testing, and it’s indicated on the device. The third one has been heavily modified (you can see a lot of wires), probably by the engineer who was testing it, for experiments. It worked, according to DongleBookpro, but it no longer does.
