Following Superman vs. the Elite, the original DC animated film out next month, the next Warner cartoon movie release will be The Dark Knight Returns Part 1 (as revealed in the special features for Superman vs. the Elite).
The Dark Knight Returns Part 1, based on Frank Miller’s classic graphic novel, is due out in fall of this year, with Part 2 following in 2013. Peter Weller, best known as Robocop but always Buckaroo Banzai in my heart, voices Batman, with Ariel Winter (Modern Family) as Robin. Harvey Dent is played by Wade Williams, and Michael McKean is Dr. Wolper, a psychiatrist who lets the Joker out of Arkham Asylum.
The Hollywood Reporter has an image gallery, from which these pictures were taken.