An Australian cinema website has posted a run-time for The Dark Knight Rises and they are pegging it at 2 hours and 40 minutes.
There have been rumors circulating around that the film will be 3 hours long, or somewhere in that ballpark, so seeing a 2:40 run-time doesn't really surprise me. If I remember correctly The Dark Knight was about 2 hours and 30 minutes so it's nothing unheard of, especially for a Christopher Nolan film. Inception was long, too. Either way I will be seeing this movie. I'll do what I did before The Girl with the Dragon Tattoo and dehydrate myself 2-3 hours prior to going to the theater so I don't have to step out.