When we learned that WB was putting the (very) early touches on a "Justice League" movie, the first question asked was "Will Superman and Batman be involved?" And now we might know the answer to that question.
Actually the first thing I wanted to know was "When will it be out?" but the Superman/Batman thing is a very good question. One source seems to know the early answer: "Batman is 100 percent going to be in the JLA movie they’re developing at Warner Brothers."
So there. For now, I guess. I bet this movie takes at least five years to hit the screens, if the project even gets out of the screenplay stage, that is. But DC Comics really wants their particular slice of the "team hero" vibe that made the "X-Men" trilogy so darn popular … so why not? If you’re gonna do a Superhero Team, you may as well invite your heaviest hitters.
Source: IESB.net