A Japanese company can now use software to animate a still portrait:
http://www.youtube.com/watch?v=KmSVoWxlDmE

Info in English:
http://blog.scifi.com/tech/archives/2007/09/17/motionportrait.html

On the Japanese site you can see many different still faces animated to follow your cursor:
http://www.motionportrait.com/about/index.html

It's my prediction that in the next 15 to 20 years or so that Actors will just simply lease their image and voice print. They'll go in for a full 3D body scan and voice sampling, walk over to the cashier to collect their fee, and they're done.

Film makers will then just take those scans and have the "actor" do or say anything they wish or imagine. We're already most of the way there.

This is just another step closer to being able to do it in real-time.

Wasn't there a movie about that? I can't remember the name but I remember a scene where the actress had to performing a diving volleyball shot over and over and over again, because she didn't meet the computer's layout of the commercial. In the end I believe the director had the computer replace her with a virtual actress and then was plannng on getting rid of the real actress (perfect shots every time).

Another movie along this theme is S1m0ne.

Yep, saw S1m0ne back when it came out. I went to see it to specifically see how it dealt with just that premise - using virtual humans as actors instead of real people. The thin, predictable plot and the "make virtual human" button aside, it had some interesting sociological foreshadowing. Imagine the virtual world of Second Life, but photoreal.

I can't place the other movie you were describing.