At the Produced By Conference this weekend, Nolan simply said "No" when asked if he would be making any more Batman movies. “Mainly, because I’m superstitious, but I said to my brother [and sometimes-writing-partner Jonah Nolan] that I didn’t want to save anything. We’re never on a specific trajectory, but I always viewed Bruce Wayne’s story in three parts. I didn’t want to hold anything back," Nolan explained. "I think you learn so much from the audience. You don’t know what you’ve made until you’ve put it out there.”
And that's about all there is to it, and it's not that surprising. He's still a young director (age 41) and we'd guess he wants to try some new things, and tell some different stories. And after "The Dark Knight Rises," which looks like it's shaping up to have the grandest scope yet of any of the Batman films, we figure he'll have said everything he's wanted to in that series. So savor all you can out of "The Dark Knight Rises" because that's all you're going to get.
In related news, Nolan continued his hard stand against digital filmmaking. Saying that digital projection “is reducing most theaters to showing TV commercials,” Nolan said that he “didn’t have any interest in being the research department for an electronics company.” But he's not a total luddite, he's just waiting to be convinced. “When it is as good as film and makes economic sense, I’d be completely open to it,” he says. No word yet on how he feels about 48fps.