>The D800 will have a DX mode in which you can use your DX >lenses. I THINK part of the photo will be cropped down a bit, >but with the size of the sensor I don't think that will be a >big deal.
DX mode does not crop a photo. The image circle on the sensor cast by a DX lens is smaller than the image circle cast by an FX lens. Therefore, the image circle activates and smaller part of the sensor. The D800 shooting a DX lens produces a 15.3mp file as a result, instead of the 36mp file it would produce with an FX lens.