BBC news has a story about a company which is trying to get computer generated characters (in both games and movies) to move in a natural way on their own.

Based on prize-winning work carried out largely at Oxford University in the UK, researchers at NaturalMotion have developed a new way of animating virtual characters in games or films.
They have created computer characters that use artificial intelligence to learn how to produce their own body motion.
"The potential for this is truly interactive characters in computer games," said NaturalMotion Chief Executive, Torsten Reil.
"So, if it was walking over a swaying bridge, the character would react to the swaying."

Full story here