This break-the-rumour but yet rumour report is in a firm tone, cited source of information is being the French CDI magazine!
http://www.photographydailynews.com/2012/02/nikon-d800-breaking-news/
So, what we have is the ever highest pixel count 135 DSLR in FF, ISO up to 25600, packed in a magnesium alloy body, with a built-in flash (which Canon never gave us for their FF models!), 1080p/30 frames Full HD video, 100% FF optical viewfinder, up to 6 fps in 36MP(!) with battery grip, to be sold for a suggested retail price of under 3,000 Euro..!
Once again, I think this report is true, it coincides with other more sensible rumours. For example, this one tells the same set of specs and it shows a copy of invitation card from Nikon Thailand and it is also cited for the source of information, for a professional guy who regularly posts at the Sina mini-Blog with his net nickname..
http://forum.xitek.com/thread-965910-1-1-1.html
(in Chinese)
After all, who said that Full Frame DSLRs are dying and EVIL (ILDC) cameras should be the future? I bet the D800 is going to be stronger and it will write a new page for the history of photographic gear! Frankly, I think that even the IQ of the 645D is endangered, for just 1/3 of the price we've got nearly the same pixel count and much the same IQ but far more features and most importantly better portability and the ever strong machine power, I believe.
Btw, what will Canon respond? Well, my Canon L and prime lenses are still collecting dust for waiting a better Full Frame body in "affordable" price! :-(
As for Pentax's current situation, there would be quite probably no FF in the meantime (no matter DSLR or ILDC). But I think the D800 sets out a good thing, that is, there is still new 135 FF sensor being newly designed and supplied (possibly by Sony?). That means that either Pentax could use the new sensor, or at least the price of the older sensors of the last generations could be reduced, if they have not yet been discontinued.
Last Related:-
The New Nikon D4, 16.2MP, 10 fps, $6000