Quick Summary: In the future, Jake, a paraplegic war veteran, is brought to another planet, Pandora, which is inhabited by the Na'vi, a humanoid race with their own language and culture. Humans cannot breathe Pandoran air, so they genetically engineer human/Na'vi hybrids known as Avatars that can be controlled via a mental link. Jake falls in love with a Na'vi princess and becomes caught up in the conflict between her people and the human military who are trying to exploit their world.
On a sidenote, I got to go see 16 minutes of footage last night in 3D and WOW! The 2D trailer doesn't do this movie justice... at all. I've never seen anything like it, it was like being in another world. The 3D isn't used as a gimick with things flying at your face. It's used to add depth and spacial awareness to everything you see, and it works. The CG characters have incredible detail and their facial expressions are very good. You simply have to see it in 3D.