I am very excited about the D800 and yes I feel it is approaching the perfect camera:
- professional video, uncompressed or compressed as needed. - crazy high res. That bride shot and the D800E landscape examples floor me. Amazing. - and to top it off on downsizing its ISO performance meets (or exceeds) the D3/D700! Not too shabby (and more or less completely unexpected).
The 4fps is perhaps the D800's main limitation. But I can say for the past year and a bit I dropped down from 8fps (D300+grip) to 6fps (D7000) for wildlife and I definitely do notice that difference but I willingly pay the price in that scenario because the D7000 sensor results are better. So one can make a sacrifice on fps, I know from experience.
The other thing is that the D800 is not a D4 in terms of probable carefree high ISO. But careful high ISO is looking promising. To digress a bit from the OP the perfect 1-2 combo is a D4 and D800 (or maybe D4/D800E)