Fox just announced that James cameron’s next movies will be Avatar 2 and Avatar 3. The first Avatar sequel is slated for a release in December 2014, and Avatar 3 should be released in December 2015 release. With the first Avatar movie James Cameron only scratched the surface of the stories he wanted to tell and the creatures and world he wanted to create. So now he will continue to expand his vision with Avatar 2 and Avatar 3.
From what I heard Avatar 2 will explore the interior of Pandora (and possibly its oceans) and the story may bring us to Pandora’s neighboring moons.