Ahem, this is the answer from EPIC.
The fun part is, this is just some sort of an updated version of Unreal Engine, so they are not still naming it as Unreal Engine 4, instead they are going for 3.971
http://www.youtube.com/watch?v=RSXyztq_0uM&feature=related
Demo Analysis -
http://www.youtube.com/watch?v=Eq1wUEkkEw8&feature=relmfu
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The lighting and shadow technique is totally awesome … They got under their asses a lot of secrets there