You'll love it - it involves Batman. I know you want to keep the Batman money train alive even in the aftermath of Nolan's record-breaking Dark Knight Trilogy, and I know you want to instantly get audiences hyped for the Justice League movie you're so keen to make in the wake of The Avengers taking the world by storm.
So here's how you do both...
Use Batman as your very own "Nick Fury."
I don't think WB should just steal the entire playbook from Marvel's successful lead-in to The Avengers, but they could do with glancing at a page or two, and this one might be the most important for them.
This project as a whole is really odd for me. For me, this won't be "the first time it's all come together" the way it was for a truly ambitious cross-film Marvel project. I HAVE a great Justice League already. I've seen several amazing pieces of Justice League media courtesy of Bruce Timm and the DC Animated Universe, 3 movies and a vast TV show continuity that stretches from the legendary Batman Animated Series begun 20 years ago all the way into the last episodes of Justice League Unlimited. So there's already a pretty high bar to clear in my estimation - and honestly, if WB has any sense they'll consult Bruce Timm on this project extensively, if not put him in charge of it outright.
I really want this JL project to work out for WB - they honestly need it now that Harry Potter is over and the Tolkien well is drying up, but more than that I love what it could mean for comic fans. See, I refuse to "pick" between Spider-man and Batman, between Superman and Iron Man. I'm just as invested in Gotham and Oa and Cadmus as I am in Manhattan, Wakanda, and the Xavier Institute. If WB succeeds it can only mean a great time for superheroes everywhere, even as the success of Iron Man was great for the idea, not just the publisher.
And if it fails, you can bet that we'll see far fewer risks from one of the biggest movie studios of all time. No matter how you look at it, that can't be good for the industry.