James Cameron's new movie Avatar CGI usage.

I was watching the teaser (http://www.apple.com/trailers/fox/avatar/hd/) and found myself wondering where they were using CGI. It appears to me to be the landscapes, the blue guys (avatars i assume), machines, computers, and air and space craft. Now normally thats what you would assume, but in so many instances during the teaser it looked like the faces of the actors were CGI as well at some points. Anyone know the lowdown?