There have been new developments in this. Bethesda claims this is a composition of multiple, real screenshots. This is of course something I had to get to the bottom of. Looking at the shadows, the light reflections, and the background sky, I have extrapolated some interesting data. anolyzing the shadows, they do seem to originate from the source of light naturally. However, there are some slightly jagged edges that indicate towards the theory that these are from the actual game. The clouds clinging to the mountain, however, seem to be touched up, if not wholly painted by hand. Now, it is plausible (yet unlikely) that Bethesda would go for such an art direction in their game. But you never know, benefit of the doubt here.
If you now look at the top line of snow in the bottom (under first rock line from bottom) center to left area you will see an area that is very reminiscent of past Bethesda games and their "weird-landscape-textures-at-an-angle" syndrome. This is arguably unique to Bethesda, and either this validates that it is in fact a screenshot - OR it is a clever ruse! A diversion, a ploy!
But then it hit me. I had looked at it all wrong. I flipped the picture, inverted colors and everything you can imagine, and I came up with http://i55.tinypic.com/i25c80.jpg. If you look very closely, there's a frog. A toy frog, in fact. Conclusion? You tell me.