Yesterday, 30th June 2008, Nikon announced the second full-frame DSLR: D700, as a mix from previous D3 and D300 with, of course, some improvements.
The ISO range is 200-6400 in normal mode, and can go down to 100 and... 25600 (!!) in extended mode. Nikon with full-frame camera has introduced this unbelievable high sensitivities, that are actually quite usable since the sensor size is large (full frame sensor with not-so-many megapixels).
The 3-inch LCD is the same of D3 and D300 while a horizon indication superimposed in the Live View is a new nice addition.
All the D700, D3 and D300 share Nikon's Multi-CAM 3500 exposure system though it is called slightly different in the three models (Multi-CAM 3500FX or Multi-CAM 3500DX).
The D3 and D700 have similar weather sealing / resistance, though the presence of a popup flash in D700 may possibly be a little weakening point with this regard.
A 24 pages document on D700 published by Nikon Japan can be found here.
D3 or D700?
The D3 (Nikon full-frame flagship) has 2 card slots, while the D700 has just one, D3 performs higher burst rate (9/11 versus 5/8 of D700) and higher shutter life, besides some other plus, but the D700 is quite cheaper (it will be sold initially for about 3000$) and have some good extras (like dust shake, built-in flash, lighter body), so I think it is a very good competition to its bigger brother.