The Blender foundation's fourth open movie project "Tears of Steel" has been released today, and if you haven't seen what you can do with open source software yet I recommend you have a look it's definitely worth it
The 12 minute movie was made entirely with Blender and other open source software running on 64 bit Ubuntu workstations.

An about page

http://mango.blender.org/about/

On youtube

http://www.youtube.com/watch?feature...&v=R6MlUcmOul8