In an interview with The Los Angeles Times, Chris Nolan has gone in to great detail about his decision to film the upcoming movie in 2D IMAX rather than the popular 3D format which has become a popular trend in Hollywood since the success of Avatar last year. Here is what he had to say in full:

"Stereoscopic presentation would have significantly changed the feel of certain 'Dark Knight' scenes, such as rooftop and aerial shots in Hong Kong that created vast and startling night vistas. There’s an intimacy at times with spatial illusion of the 3-D effect and we didn’t want to lose scale."
"Our ambition for the third movie is to complete a story that has begun. This is not starting over, this not rebooting. We’re finishing something, and keeping a consistency with what’s come before has real value. We’re looking to do something technologically that’s never been done before. Our ambitions are to make a great movie."
The Dark Knight Rises is set to be released on July 20, 2012!