D3 or D700?
Probably the best feature of the D3 is it's ability to perform in low light. It is quite simply the best digital SLR where hi ISO shooting is concerned; shots at 6400 are smooth and lack noise and when noise is evident, even at 12500, it looks very similar to film grain and therefore very acceptable.
The D700 promises this too, it also shares the focusing, said to be almost eery in it's ability to lock-on to subjects as if by magic; the weather sealing is to the same standard, in terms of robustness, the pop-up flash makes the D700 less sturdy, but means that fill-in light is available as is 'commander mode' to fire Nikon Speedlights. The D700 also has a dust reduction system, important to some and missing on the D3.
So what does the D700 lack? It shoots at 5 frames per second, 8 with the MB10 and either the EL4 battery or 8 AA's against the D3's 9 FPS or 11 in DX mode, speaking of which the D700 does FX and DX only, there is no 5x4 cropped mode... The cheaper camera (£1999 against £2850) sports just one card slot, a viewfinder which shows 95% of the frame, and it is said, more distinctive focusing points (not necessarily a benefit).
If you've just bought a D300, then the differences are few, largely the FX sensor which in addition to it's low light ability gives you the green light to buy really expensive optics!
If you want a great landscape camera, then hang on for the D3X which is likely to be launched on 23 September (Photokina Show) this will probably be 5 FPS but 24 mega-pixels - i.e. less of a sport/photojournalist tool, for most though the D700 looks to be a great camera to buy - I might just!
The new brochure is a 10Mb download here