SketchFactor over at Bungie.net has posted the results of the "Ask the Cananimators" feature interview, with answers by anim8rjb and bentlama. While the majority of the answers were with tongue placed firmly in cheek, and related to the genesis of Canadian Bacon, the relative coolness factor of the OHL and the CFL, and the prospects for the Toronto Maple Leafs, some Halo info did creep in there from time to time:

NW: We actually use IK for most of our animation. IK on the arms and legs, feet and other areas. For the most part we are really used to animating with IK. We use FK for the spine, neck, head and wrists and toes. Our animation rig is a mix of a lot of things, and through the power of MEL, it is simple to use and quick to animate with...those are the most important features of any animation rig. Thanks for asking, and please keep posting more questions like this.

Be sure to give it a read. Thanks to Louis Wu at HBO as usual.