Yeah, if you look at other videos and pictures, you'll see that fog and clouds are rendered dynamically.
And as you can see, the fog in that pic is drawn/painted.
Your system can already run circles around 360's and PS3s and can run the game on medium-high settings which is already beyond a 360.
It's for example like your PC is 5 times faster than the console, but the game only runs twice as good on it (with same settings).
We will see, how good Skyrim will be optimized on PC.
As I wrote, Bethesda usually does an "ok" job at it imo. Not perfect, but still good.