I'm assuming, according to Bethesda's history of strictly
timed exclusivity, the XBOX version will include the new locations and all that, along with the Kinect support, while the PC and PS3 versions will only include the new locations, quests, etc.
The only difference between the two content-wise is, obviously, Kinect support.
If they add quests and content that is only available for Xbox, I will absolutely positively not buy any thing else from Bethesda ever again. Not games, not DLC, nothing. The Kinect thing I don't care about. Quests are a different story altogether.
TAKE HEED, BETHESDA!
This is the reason I doubt Beth will ever make any legitimately exclusive content.