An image that surfaced on Imgur and Reddit shows a wall that appears to be in either Warner Bros Animation or Cartoon Network offices. The original poster doesn't identify where the image comes from, who took it, or where it was taken, unfortunately.
But the op does point out a prominent JLA poster to the far right of the image. The poster is alongside known new properties like Be Cool Scooby Doo and Wabbit (both launching later this year) and current series Mike Tyson Mysteries and Teen Titans Go!, which lends credibility to the idea that this is a new series. While folks at Warner Bros haven't yet responded to requests for comment, the design and apparent lineup on the poster doesn't fit with any of the direct-to-dvd animated movies that are known to be in development (which have largely been following the New 52 lineup and design from DC Comics).
The poster appears to show: Superman, Wonder Woman, Batman, Martian Manhunter, an unidentifiable female, Firestorm, most likely a Green Lantern or Flash, another female, a Hawk-person down at the bottom, and five cut-off partial characters. It looks like a giant line-up, somewhat similar to the final cartoon in the "Timmverse" era, Justice League Unlimited, which had a rotating cast that pulled form all across the DCU. The characters are in silhouette, and the image is fairly small, but it sure is intriguing.
We'll keep you up to date here at ComicBook.com as we hear anything directly from Warner Bros.