Hey MCDesigns,
i work in the concept/pre-production side...so i'm not too familiar w/ the production side of things. However, most of the CG work was done over at WETA, and they use all types of software. Most films are not made on "off the shelf" stuff like Maya and MAX. We usually have internal software written directly for the studio. ILM, Digital Domain, WETA, etc. all use their own. However, packages such as Maya and SoftImage are pretty common for building models and such. My friend (Neville Page) used a lot of Zbrush to design the Na'vi and the various creatures of the planet. Then WETA imported those models into their own 3d package.
Avatar used some very state-of-the art motion capture. Ontop of that, it was done in 3D...which means every 3D frame has to be rendered out twice at slightly different angles....i still can't believe how fast they put this film together. Yup, the processing power is crazy. Just to give you an idea, to visit a Render Farm (a large room filled with PCs....as in thousands), you have to put on a thick winter jacket. They keep these rooms at super-cooled temperatures to prevent CPU burn out. The Render Farms rooms look sci-fi themselves! Imagine standing in a large, freezing cold room, filled from floor to ceiling with PC boxes (no monitors....they are controlled remotely)....and little green lights are flashing all around you....and all you hear are industrial fans noises...
I'm gonna go watch it again next week....once is not enough. Too much detail overload!
-feng