Here's an excerpt from an article about it:When asked if there would be a third installment, Bale wouldn't confirm or deny. "Um, look, let's wait and see." When the magazine "mistakenly" referred to it as a sixth installment, Bale was quick to correct them, and elaborate on the possibilities of a trilogy. "No, no, no, no, no. Part 3 is what I'd consider it, yeah, I don't say part 6. Batman Begins - that was the beginning there, with all due respect to the others. We are re-creating this. You know, obviously the decision is out of my hands. I would, knowing the Dark Knight story, I would like very much to complete a trilogy. And I think that knowing the story of The Dark Knight, it leaves you anticipating something that really can get very, very interesting for a third. Now, the question would be: Is Chris going to be doing it? Because to me I find it tricky to imagine working on it without it being a collaboration with Chris."
Here's the link to the article: http://www.cinematical.com/2008/03/17/a-third-batman-christian-bale-says-wait-and-see/