I think D7000 is almost definitely better than D90 in terms of ISO performance, but I'm not sure it can be compared to D700. Notice that D700 has 2303 ISO score, D90 977. It's more than 1 stop difference. When all said and done, I will be surprised D7000 can get ISO score better than 1500, even if it does, still far from catching up with D700.
From the flickr ISO shots you posted in another thread, I think they are not that much better than D90 would perform under the same situation.
I remember someone posted pictures of D3100, and many people think D3100 is comparable to D700, turns out D3100 cannot even beat D90. I too hope D7000 is a drastic improvement over D90, but I'm less convinced now than a couple of months ago.