A recent update on
bungie.net talks about some of the work the cinematic team has been doing along with bringing in the guys at D.A.M.N. FX, who up until this point have been working on Halo 3 away from the studio, but have recently been brought in-house in order to work on some of the key cinematic screens in the game.
These animators are definitely qualified having worked on a number of films including: The Shrek trilogy, Lord of the Rings, King Kong, Happy Feet, Transformers, and Madagascar.