Kara by Quantic Dream - While this is actually a tech demo and not a short film it's amazing enough to be considered one. Not only is this fantastic from a technological standpoint, but it also raises many questions about the ethics and morality of robotics and artificial intelligence.
Quantic Dream's "Kara" PS3 Amazing advancement in Computer Animation, and a great new engine for video games. The effort to create this demo is mind blowing. The little mini movie is inspiring me to write and illustrate another story. Enjoy.