Have you got a date and specs for the D800 yet?
I believe this was well documented on the Nikon Rumor site while they are not official yet of course. The date is Feb 7th and the spec would be:
•36 MP sensor (7360x4912)
•100% viewfinder coverage
•Improved AF with face recognition – the D800 will still have 51 points AF point
•CF+SD memory card slots
•USB 3.0
•ISO range: 100 – 6400, ISO LO @ 50 and ISO HI-2 @ 25600
•The screen will be larger than 3 inches (probably 3.2 in.)
•The D800 will not have built-in GPS
•Expeed 3 processor
•There will be two different D800 versions/models, one with the antialiasing filter removed
•4 fps continuous shooting, about 6 fps in DX mode with optional battery pack
•Video modes: 1080p/30/25/24 and 720p/60/30/25/24
•Headphone jack, can input from an external device such as a PCM sound recorder
•86k pixels RGB sensor
•200,000 shutter cycles
•Uncompressed HDMI video out (just like the Nikon D4)
•See those cropped Nikon D800 samples at high ISO