They have a 2 Petabyte disk array, 10gbps networking, and 35,000 cores (4,000+ HP blades) in their data center, and still it takes 48 hours to render some of their graphic sequences.
According to Paul, Ubuntu is at the core of all of this,
Ok, I still have to see the film. Anyway, I think that it's fairly impressive just reading about the computational power that nowadays it's needed to produce a film like Avatar! Additionally, I must admit that my "open source" side is pleased to know that they are using Ubuntu on their machines... ;)