Synthespians

This is a pretty amazing video. The "person" being interviewed is synthetically constructed, using a number of images taken of a real human being to generate all of the facial expressions.

It was created by a company called Image Metrics, who are the people behind the animations in Grand Theft Auto IV.

Update: I've replaced the original YouTube video, which seemed to have some kind of glitch partway through. This seems to be a superset of the old one.

Thanks to io9.