Considering the D800 when they come out. I incorrectly assumed that my AF Zoom-Nikkor 80-200mm f/2.8D ED Lens was a DX only lens. If you look at the specifications, it says....
Format Compatibility Nikon FX/35mm Film Nikon DX
So, it will work on both FX & DX formats.
I'm assuming though that the reach of the lens when mounted on the FX body will be less than on the DX. Meaning that compatibility means that it will mount and function, but the focal length will be different.