The D800 image that leaked few hours ago on several of the official Nikon websites is now gone, but several readers noticed the folder named “Jan-Feb launches” that was included in the page source:
…File=/imported/images/02. Regional Marketing Centre/BV/04. Agency/JungVonMatt/148/Web/Jan-Feb launches/Q720/PPDD/Flash Assets/111125_SLR_Prof_Banner/698x209_DSLR–(Get Original).xml
Q720 I believe is the code name for the Nikon D4.
Since the Nikon D4 just got announced, it leaves the D800 for a potential February release, probably for the CP+ show in Japan (February 9-12, 2012).
See the full Nikon D800 specs here.