Yes. One of the D3's I was playing with at PhotoPlus had been put into DX mode with the 24-70mm on it by someone before I picked it up. Had me confused for a little bit until I found the menu setting to change it.
I can't remember where I saw this (a thread here or an article on Thom Hogans site), but it may interest you... there is a list of DX lenses and their corresponding image circles at various focal lengths.
As Victor said, the 17-55mm covers the whole FX frame only from about 26mm to 55mm. Less than 26mm in FX mode and you'll get dark corners or similar. The lens covers the whole DX crop frame at any focal length.
An alternative to the new 14-24mm is the existing 17-35mm, which is an FX lens.