Here`s what I came up with, anolyzing the demo and the skyrim map:

http://imageshack.us/photo/my-images/96/skyrimmapq.jpg/

The first red circle is what you can see in the beginning of the demo:

1. There`s the road
http://imageshack.us/photo/my-images/845/roadsign.png/

2. There`s the mountain you can supposedly climb
http://imageshack.us/photo/my-images/856/mountain.png/

3. There`s the ruins on a small mountain (bleakfarrow dungeon)
http://imageshack.us/photo/my-images/810/riftenarea.png/

4. There`s the lake seen when the character uses a spell
http://imageshack.us/photo/my-images/607/lakeu.png/


The second red circle is the whiterun tundra region, it can be all seen in the demo. This is the biggest area ingame and it is a flatland, that clearly indicates what we can expect from the smaller areas which are mountainous:

1. The blue circle is the area between the mountains and the city of whiterun, exactly where the character fights with the mammoths and the dragon.

http://imageshack.us/photo/my-images/571/whiterun.png/
http://imageshack.us/photo/my-images/38/distancefrommoutainstow.png/

2. Here we can see a fort which is probably North Keep on the map.
http://imageshack.us/photo/my-images/64/northkeep.png/

This pure speculation, hope my observations are wrong.
I will leave the judgement to you.