If you're having second thoughts about the D700, you're crazy - unless you need 9 fps, in which case, buy the big battery pack, or video, in which case, buy a Canon or D3s.
Here's the reality: we're at the point with digital where incremental improvements are real but marginal, both in terms of ISO performance, features and resolution. If you're a fringe user, you'll see the difference. If not, you won't. It's true that the new stuff has 1 - 1.5 stops of higher-ISO advantage, although "why" I don't know (I think new microlenses?), and there is the potential for marginally higher resolution cameras to come out. Likewise, fluff features like video. From a handling point of view, the D700 is about as good as it gets - switches just like my old F5 and a brick-like feel. Those things won't change. IQ won't change. Resolution may or may not change.
Unless Nikon does something radical on the sensor side, which is unlikely, the D700 replacement - which probably won't be available for six months (that's a lot of pictures) won't be that different from the D700 of today.
BTW, if you look at ACTUAL resolution on these cameras and are waiting for more MP, you're not going to be blown away. Check DxO Mark, or do the math on the figures reported by DPReview. The D700 is 45 lp / mm + -; the D3x is 57, although lens matters. Velvia at 50% contrast is about 50 and at a 25% contrast about 80 or so; Ektar 100 claims about 50 at 50% for blue and green, but I'm a skeptic on the print stuff (this isn't a film / digital point - it's that getting more res. is HARD and you have to make severe compromises to get there). Interestingly, that means that after interpolation etc. the 12MP D700 is capable of outputting only about 7 - 8MP of actual data (up to 10, which is amazing, under certain circumstances), the 24MP D3x 11-12MP of output data (up to 20 under certain circumstances, supposedly).
So your D700 replacement isn't going to get much better than it is today for most applications.
A final point - the Nikon "full refresh" is 4 years, not 2. So a 2-YO body is current. Again, they have added features ("s" and "x"); the "s" is nice for sure and if it was out and available (which the D3s is not, at least on a "now now" basis) you'd get it.
I just got my D700 and I don't regret it for one second.
p.s. They do still make "bad ones" from time to time - I got one, actually, with a bad AF module.