You could say that the Assassin's Creed games have always had very impressive animation, but Ubisoft will be pulling out brand new technology for capturing animation in their development of Assassin's Creed: Revelations.
Speaking with interviewers, Lead Game Designer Alexandre Breault explained what advantages mo-cam animation capture has over dedicated facial animation capture, as seen in L.A. Noire:
One of the elements that's really interesting about Mocam is that, while it creates a lot of high-fidelity character expression and movement, the actor doesn't need to look like the character he's playing. It's a system that's able to interpolate the facial movements of one person and apply them to any model. That gives us a lot of flexibility with our actors.
They're also able to act with their whole body, as the system isn't just limited to the head. Mocam doesn't create a clash between facial expression and body movement - it's all integrated. It allows realistic facial expression, but not at the cost of actor expression as normal mo-cap does.
Having seen Revelations in action firsthand, character animations look great, but I haven't been able to catch a good look at any in-game facial animations. We'll see more from Ubisoft as we move into the Fall.