Well the rumours are starting to gain momentum, and with enough detail to begin to sound credible. Here's what I have heard:
9D will be the official designation (why a 9, I have no idea...)
16.2 MP, single digic-III processor
ISO rumors are still sketchy, but looks like only a one-stop bump, 100 to 3200 with a L and H of 50 and 6400 respectively.
Improved weather sealing and micro AF adjustment.
No word on sensor shake/cleaning, no word on auto-ISO.
My comments: My biggest need for a DSLR is high ISO for really low light shooting, and preferably a usable 6400 with auto-ISO function. I also want a non-pro body due to the smaller size and lighter weight as I carry the cameras a lot more of the time than I need 10 frames per second capture rates. While I'd prefer as much resolution as is usable, I would not give up ISO 6400 to get it, so megapixel count comes in as a secondary consideration for me.
So IF the above ISO rumor is true, then one can assume that ISO 6400 will be pretty noisy, with 3200 to be the practical usable maximum. For me, this could be the final push to the D700 as I found 6400 acceptable on it, though still a bit noisy for my tastes. Will need to see some files before I decide, but it should be interesting!