This Chilean film is from Gabriel Osorio Vargas and is the story of a bear who is stolen from his family and forced to perform in the circus. What makes this one so memorable is the way the story is told...as a story within a story that is being told through automatons built by a bear!
The Computer graphics, though very nice, are probably the reason I'd list this as my second favorite of the nominees. It's nice...but these days I've seen quite a few CGI films that are frankly better looking. A lovely film but not quite good enough to earn the Oscar for Best Animated Short in my opinion. I'll be sure to update this review to let you know if it wins, though with a Pixar short and Don Hertzfeldt's short, I think "Bear Story" has a difficult and less likely chance to win the award.
UPDATE: "Bear Story" did win. Didn't guess right this year!