At first I thought this was a one off for some crazy customer somewhere, but it seems this is legit. The news is all over the blogs and auto sites of the web (google is your friend) and Mercedes is offering this as a military version (G320 CDI 6x6), as well as the G63 6x6 seen above in this thread. They are hoping to sell 20-30 a year.
Here is a video:
Cant wait to see what sort of camper builds that will end up on this platform!