I don't think it's photoshopped. The reflections from the flash, the multiple angles, etc., I think it's a real screen.
BUT what could make it fake is somebody just making that as an image for a screensaver on their modded Xbox, and throwing it up on the set and taking the pic.
I REALLY want bungie to respond somehow. Call it a fake, or call it an early menu. Say nothing and most of us will assume it is legit.
If it is the real deal, no way it is close to final, because the menu font sucks ass. It doesn't seem to fit with Halo IMHO.