Ruh Roh! Nikon made a bad decision. Look at and zoom around on their full res sample images. Looks pretty okay for the ISO 100 images.. But look at the ISO 640 and even the ISO 320.. Reminds me a bit of my 7D in lower light. Should you REALLY have to put up with that on a $3,000 camera? Here's hoping the next 5D stays around 22mp.

http://imaging.nikon.com/lineup/dslr/d800/sample01.htm