"Man of Steel" scribe David Goyer says that despite the announcement this weekend of that film's sequel being a Batman and Superman team-up movie, the studio has yet to settle on a title for the project. Goyer tells ComicBook:
"So the next film we’re making, we’re already in pre-production, comes out in summer of 2015 and it’s–we’re actually not sure whether the title is Superman vs. Batman or Batman vs. Superman but yes, it’s–that rematch, that combination, the two guys onscreen and that’s happening."
Many have been suggesting it'll be "Batman vs. Superman" due to Warner Bros. Pictures registering domain names along those lines. However, those registrations reportedly took place over a decade ago so have no bearing on any decisions regarding the film's title at present.
Goyer is currently co-writing the story with director Zack Snyder with filming to begin sometime next year.