Nikon has announced two (actually, three) exciting new cameras: the D4 and the D800 (and D800E version). All three cameras are outstanding. I chose the D800 as I think it suits my style of photography the best.
I've enjoyed shooting with my Nikon D700 for the past three years. I expect the D800 to improve upon the D700. The D800 will offer files sizes that are three times as large--which will provide higher resolution and more cropping flexibility. The new camera should retain the same low light performance as the D700. I also expect that the D800 will have improved auto-focus capabilities--especially when used with teleconverters
One drawback of the D800 is that it requires careful technique. This shouldn't be an issue for me as I tend to use a tripod and cable release for most of my pictures. Unfortunately, the Nikon vertical grip and Kirk L-bracket isn't available right now--so I'll be hand-holding the camera for the near future. In fact, I'll probably continue shooting with my D700 for the upcoming weeks.
The D800 also offers incredible video performance. My interest is almost entirely in still photography, so I doubt that I'll utilize the video capabilities of the camera very often.
I struggled with the decision between the D800 and D800E versions. Ultimately, I took Nikon's advice and ordered the regular D800 version. Although the resolution might be a tiny bit less than the E version, the risk of moire is reduced. The regular version is more appropriate for a wide variety of subjects--which describes my photography.
My Nikon D800 is scheduled to arrive on Tuesday. I'm anxious to play with the new camera!