Most UT3 games with in-game facial animation use FaceFX, which is an automated solution for doing facial animation. As such, there are no "facial animation files", rather the ability for the model that has a facial rig with pre-defined poses to recieve animation data from a pre-recorded sound file...FaceFX does a wave form analysis of the voice, and matches it to the corresponding mouth shapes, as well as allowing tweaking of the animation generated for best results, such as adding smiles, frowns, blinks and head movement to dialouge.
I don't think I've seen actual facial poses stored as an animation sequence in any FaceFX unreal engine I've looked through via UEViewer - though you can download any of the gears of war skeletons released officially and "see" the facial animation poses in action...kinda looks weird when you see it, as it just quickly cycles through all the stored poses in exorcist-style!
So, the faces in ME are rigged and weighted for facial animation in FaceFX...but I've yet to see just the facial anim file, as FaceFX data is not suported by UEViewer. As for importing the character back into say, UDK, and re-activating FaceFX, I'm not sure about that process, so I could be talking out of my hat, so if anyone knows better, I'd be quite happy to be corrected on the matter