With The Dark Knight Rises a lot of familiar faces return, who have had previous collaborations with Christopher Nolan. Michael Caine holds the record for Nolanitis with five movies (Batman Begins, Prestige, The Dark Knight, Inception, TDKR), second would be two actors, one of them is already cast as the title role of this movie, the other is the one many fans have been hoping for.
Click more to find out who it is (spoilers?)
So this will be the fourth time that Cillian Murphy will be in a Nolan movie and (probably) the fourth time he gets a sack pulled over his head in the role of Scarecrow. I doubt he will have a very big role, I guess he will be just there as a trademark for the Nolan Batman-incarnation as a little easter egg.