Leaked Pro Mac Photo Summary
Meanwhile, a MacRumors source confirmed the authenticity of the enclosure, and Apple Legal requested the removal of these images hosted on MacRumors.
Note that the motherboard bears a resemblance to a leaked motherboard that appeared on eBay. Photos of that motherboard have also been removed at Apple's request.
Update: The case appears to match various specs that were rumored to be on Prototype cases including white speaker, front mounted headphone jack, 4x512MB RAM, new motherboard, bays for two optical drives.