There are quite a couple of updates on the upcoming Avatar sequels in the following article:
http://marketsaw.blogspot.de/2012/05/james-cameron-diving-into-avatar-2-3.html
For those of you too lazy to read the full article, here are the main points:
- James Cameron stepped back from world building, meaning another race/planet/moon in the sequels becomes less likely.
- Avatar 2 & 3 are still in the writing phase, design phase coming up next.
- There could be a fourth Avatar movie.
- James Cameron's team has spent the last 1.5 years on improving their software and virtual production methodology to save time, money and effort and on setting up their new L.A. stages.
- Battle Angle is pushed back to an unforeseeable future.
- The documentary about Cameron's Mariana Trench dive is set for a Q1 2013 release.