I'm also surprised -- and bummed -- that this fantastic artwork isn't on any of the Blu-Ray covers?:
Agreed. Maybe they figure that art didn't sell the movie enough in theaters so it won't sell it on blu-ray? It is featured inside the steelbook, so at least it's somewhere.
Anyway, I pre-ordered the Target one because I think it will be a digibook. Apparently for recent releases, Target has been putting out digibooks with slipcovers over them, like this:
(I love the steelbook, but I don't have Prometheus in a steelbook. These things need to match on the shelf!)