As it is always easier to give the bad news first: it was reported at this panel that the remaining 13 episodes of the second season will be the show's last. [Update: Sorry guys, we somewhat misheard this. The show is indeed ending, but they still have the second half of Season 2 to air. There will then there will be a 13-episode Season 3, which will be the final one. Season 1 and 2 each consisted of 26 episodes each.]
Fans of the series were vocally upset at the end of this loved program, with those sentiments being shared by the talent on the panel - especially by the voice of Batman, Diedrich Bader, who called it the best gig of his career. Fortunately for the panel, everybody has future projects to go to, so nobody will be left without a job - this announcement included a hint James Tucker was working on an all new Batman series.
http://tv.ign.com/articles/110/1108206p1.html
It is getting 65 episodes. It seems like most American cartoons these days have a much more limited run compared to those in the past.