A DC Comics scribe doesn't see a Justice League movie coming together because the characters involved are too special.
If DC Comics were to counter Marvel's upcoming Joss Whedon Avengers movie with a team-based movie of its own, it would have to bring together the Justice League. Though Marvel has no trouble featuring Iron Man, Thor, the Hulk, and Captain America in one flick, prominent DC Comics scribe Geoff Johns doesn't think the same could happen with the top heroes of his company.
The Justice League is a who's who in the DC universe, featuring Batman, Superman, Wonder Woman, Aquaman, the Flash, Green Lantern, and Martian Manhunter as core members. According to Johns, DC bringing all of these top-tier superheroes together in a Justice League film seems unlikely.
At a New York Comic Con panel, when Johns was asked whether the Justice League could come together on the big screen someday, he said: "I'm going to speak frankly: I think our characters are bigger than Marvel's." In his opinion, it'd be better to focus on each individual hero of the League rather than "smashing them together." A Justice League movie was given a tentative green light by Warner Bros recently, but if the movie does eventually come together it might not feature Superman or Batman in the roster.
Marvel bashing aside, Johns is pretty much right: Superman and Batman alone are better known heroes than the entire roster of the Avengers. Still, I doubt there's anybody that wouldn't want to see the true Justice League come together on the big screen someday. Though it seems like DC would be missing out on something that would likely draw in plenty of movie goers through a proper Justice League production, it might be too complicated to put DC's big names together properly in a two hour film without devaluing some of them. It'd be really cool for fans though.