So, yes, Warner Bros. is still trying to get a Justice League movie together, with "Gangster Squad" writer Will Beall being the latest to take a crack at the long-stalled project. Honestly, that Warners is working on this isn't news until they say YES to the script itself (studios comission scripts for potential projects all the time) and I suspect that the only reason we're hearing about Beall's script officially is so to bury the less positive announcement that "Wonder Woman" is getting a script from the writer of the "Green Lantern" movie. Ah, well.
It's simple math: "The Avengers" is the movie of the moment and (unless "Dark Knight Rises" or something else pops in an absolutely stunning way) probably THE pop-cultural event story of Summer 2012. If you're a studio executive and you aren't a least exploring options for a "team of superheroes" movie of your own, you are not being responsible to your shareholders. And if you already OWN a team of superheroes - say, one that's already more well-known and widely-recognized than "The Avengers" - if you aren't already MAKING that movie you don't deserve to hold your job.
What I like about this is that they don't seem to be waiting around to try and do a multi-film buildup like Marvel did. It could end up working out that way anyway - I wouldn't be totally surprised to see a toe or two being dipped in the continuity-waters in "Man of Steel" - but I don't know that it needs to. "The Avengers" was a different story - apart from The Hulk, almost no one outside fandom knew much about the other characters. Everyone knows who Superman, Batman and Wonder Woman are. Even Flash and Aquaman are more widely-known that Iron Man ever was before the first movie. To my way of thinking, the smartest move Warners could make would be to make JL a top priority, get people under contracts and then figure out who gets movies of their own when the numbers come back.
And, honestly... while continuity-driven shared-universes are fun, Warners painted themselves into a corner in that regard by agreeing to Christopher Nolan's alleged "nobody touches anything Batman but me!" demands (which may still hold for Superman as well); and starting now would put them way behind the curve.
Obviously, my "best case scenario" hope would be that Warners has it's shit together and the already-cooking de-Nolanized Batman, "Man of Steel," Wonder Woman and Flash movies are being built to tie-in to this; but if not I don't think that many people would mind JL being a seperate thing, partly because (again, unlike "Avengers") these characters are bigger than any actor playing them could ever be: Whoever's wearing the Superman costume IS Superman.