It's almost identical to the D70s in most regards, except:
Lenses: Works fine with old manual focus AI and AI-s lenses in A and M exposure modes. Tiny possibility it may also allow P and S exposure modes with manual lenses.
Viewfinder: Same as D200.
AF: 11 zones, from the D200.
Resolution: 10 Megapixels, up from 6.
ISO: 100 - 3,200
Flash Sync: 1/250, down from 1/500.
FPS: 3
Memory: Takes SD cards, not CF.
LCD: 2.5," up from 2.0"
Mechanics: Top panel illumination now switched on by twisting the power button, just like D200, D2X, etc. The D70 had a separate button. The D80 is an improvement. Slight rearrangement of buttons on rear. Dedicated AF selection button on top of camera, a big improvement from D70 which required a menu to select between AF-S or AF-C.
Price: $899.
Availability: Like most new Nikons, it won't be on shelves and in stock for months. Get yourself on a waiting list and be patient. The D200 and 18-200 VR aren't readily available, and they were announced nine months ago. If you need a camera today just buy a D70s or D200 and don't worry. You'll make thousands of great photos every month with a camera you own and no photos with one for which you're still waiting. I have a whole page about managing obsolescence here.
The D80 will be announced via press release, so just look here (international) and here for Nikon USA each day. This is where all the magazines and other sites read the data, so you may as well get it from the source the day it hits.
PERFORMANCE
Most likely the same image quality or slightly better than the D200.
Identical materials and robustness to the D70.
RECOMMENDATIONS
As always, if you have something to shoot today, get a D70s from stock.
If you can wait, forget the D70 and get your order in for the D80.