Yes, it's concept art.
And yes, it's fantastic.
You can see it in the "Concept Art" section of the Skyrim site, along with some other pieces I'm sure you'll be impressed by.
Its the first shot in the Screenshot area. Concept art is lower down the page.
I guess everyone's divided on what it is.
I think the Creation Engine must be more powerful than we expected.
We need an official statement from Beth on this!
They already did. Its a screenshot. When the GI article first came out someone made a thread about being cheated, because there were supposed to be a certain number of screenshots and there supposedly were not. Then Pete, on twitter, pointed out that the mountain shot was the "missing" screenshot.
Sometimes devs will touch up screen shots. I won't accuse Bethesda of this though. I don't know their history.
If it is a screenshot, it's from a high-end pc hooked up to the damn sun.
Sorry. All the screens so far are from the 360 version.