Nice!
This camera is presumably tied with the D3 for the best low-light performance on the market, is built to flat-out pro standards (full weather sealing, Nikon's famous (and beautiful!) circular viewfinder window, etc.), and actually shoots very quickly, particularly with the grip option. It'll cannibalise a lot of D3 sales, but realistically it will also put serious pressure on Canon's 1D-series cameras. Price is important even for pros, and 8 fps (with the grip, which of course does cost money too) is nothing to sneeze at, even for sports.
Here's a few sample images from Nikon. They don't tell us anything new, but check out the fourth image (woman in church) to remind yourself just how good that sensor is. (The flare resistance of that Nano-coated zoom is quite special too.)
Interestingly, the viewfinder is of slightly higher magnification than the D3's (0.72x versus 0.70x). They undoubtedly use the same prism. This places the D700 in second place on the DSLR viewfinder magnification list (after the 1Ds Mark III with 0.76x). Much larger than the 1D Mark III (0.59x).
Now, will Canon be brave and put a non-"pro" $2k full-frame DSLR on the market, or release another excellent but strictly me-too product at $3k? If the former, things will get interesting!