Michael here. According to the MPAA's site, Avatar has been rated PG-13 "for intense epic battle sequences and warfare, sensuality, language and some smoking."
The PG-13 is no surprise given Cameron's previous statements that he was gunning for that rating. But the rating reason is interesting, and makes it seem like Cameron has really pushed the PG-13 as hard as it will go in multiple categories.
Smoking? I wonder who lights up in the film? I'd bet on Selfridge.
