TED Talk : Paul Debevec animates a photo-real digital face

Creating a convincing CGI human has always been the holy grail of computer graphics. I say, convincing, because many attempts have been made before but they all end up in the realms of creepiness.
Its is tough to create a CG human mainly because we are used to recognizing human emotions and the little nuances of our expression that the moment we see something off, we find it robotic and lifeless. All our lives we have been interacting with other humans that we have strong memories of  human reactions, which is why its easier to create CG aliens and other creatures because they are all based on concepts and one's imagination and no one really knows their behavioral attributes.

Attempts before [Final Fantasy, Beowulf] have all been a roller coaster ride in the Uncanny Valley - The Uncanny Valley is part of a hypothesis of robotics that posits that a human will have greater empathy for a non-human entity (like a robot) as its appearance and emotion become more humanlike. The "valley" refers to a strong negative response humans have to an entity that is nearly human, but still inauthentic enough to seem unnatural and therefore "uncanny".

Paul Debevec is a researcher in computer graphics at the University of Southern California's Institute for Creative Technologies. He is best known for his pioneering work in high dynamic range imaging and image-based modelling and rendering, Debevec's work have been used in several major motion pictures, including The Matrix, Spider-Man, King Kong etc, his research with Facial Re-lighting and Dispalcement driven performance is really mind numbing and fantastic, slowly bridging the gap in the uncanny valley of photo real CG.

Recently the development the Light Stage where an array of lights would record an actor from the waist up delivering a short performance and then relight the performance in post production to match any lighting setup, since the performance was shot with a vast array of lighting combinations per second.

All these developments are bringing us closer to making a very convincing computer generated human. The above clip of Emily is the closest I have seen in terms of a believable result, the acid test would be to see how it holds on an extended performance.