Man of Steel director Zack Snyder hinted that the Superman film, due out June 14, 2013 (see "Warners Flogs 'Man of Steel'"), will lead into Warners’ Justice League (see "Warner Bros. Slates 'Justice League' Movie for 2015") in an interview with the New York Post. The Post asked Snyder whether he’d been talking to the studio "...about integrating Man of Steel into a larger superhero universe," and got a non-denial denial. "I can’t really say anything to that, because that’s a big spoiler," Snyder said. "I will say, yeah, they trust me to keep them on course."
Marvel has shown how to tie superhero movies into a superteam spectacular, and it would not surprise if DC and Warners followed suit.