Before James Cameron started work on Avatar, he was long rumored to be working on an adaptation of the Battle Angel manga series. While many supposed that probably would never happen, given that Cameron is working on completing the Avatar trilogy, he apparently still has some plans to do it.

“I’m obviously going to be pretty busy for the next five years [with Avatar 2 and 3].  And so I had to consider, ‘do I hand this project off to another director?’  And then I thought,  ‘No, I love it too much,’ said Cameron when asked about Battle Angel. “It’s such a rich world. What I’m going to do is take the spine story and use elements from the first four books. So, the Motorball from books three and four, and parts of the story of one and two will all be in the movie.”

Source: Collider.com