I am guessing it will be UE 3.5 with heavy tessellation, particle lighting and reflections (closer to the Samaritan demo). Maybe even see some physical based rendering? the trailer sure looked like it's using some elements that are similar to the Infiltrator demo.
Trailer was multi-million dollar CGI from Blur. Dont look too deep into it.
This was announcement trailer for Arkham City http://www.youtube.com/watch?v=muCtJsy-d9w&hd=1