Batman: Arkham Asylum will be turned into an animated movie. It'll be based on the Rocksteady Studios game rather than the comic.
In an interview with Comic Book Resources, producer of the Justice League: War animated series James Tucker confirmed that Batman: Assault on Arkham will be released at some point in 2014 and will re-tell the story of the Batman: Arkham Asylum game. It will be directed by Justice League: War's Jay Oliva.
There's no more information beyond that for the time being. We'll update you as we hear more.
We still haven't heard much about this Batman: Arkham Origins DLC, which has been tied to villain Mr. Freeze.