If you purchase from iTunes (not sure how to link for that, but it's as simple as opening iTunes and searching for Tron: Legacy) there are some extra tracks as well.
The soundtrack to the original Tron film is cheaper from Amazon than from iTunes (by $2). Both Tron and Tron: Legacy are $9.99 on iTunes.
Meanwhile, I've been avoiding reviews as much as possible. I want to know nothing more about this movie. I'm even avoiding looking at track names on the soundtrack . . . which is going to make comparing Amazon and iTunes track listings quite difficult.
Update: the extra tracks on iTunes are "Father and Son" and "Outlands Pt. II", and are each available for $.99. I just may splurge and spend the extra $2 for the extra two tracks after getting the actual album from Amazon for that incredibly low price . . .