But it will run on hardware from 5 (6) years ago: consoles -- and according to Bethesda it will "look the same as on PC apart from resolution and AA".
I'm not by any means saying Bethesda can't code for crap. On the contrary, if they got something like Oblivion (and what looks to be a somewhat-enhanced Skyrim) to run on a 3.2ghz in-order CPU and < 512mb of shared memory, they're doing something right.
I don't care about consoles and PC is a different beast in terms of performance, since there are many hardware combinations to think of and you can bet that no PC in 2006 would run Skyrim, as it is shown in the trailer, acceptably.
Remember that Oblivion had shadows removed due to performance reasons. Creation Engine's objects cast shadows all over the place.