This article on digitalcontentproducer.com gives an interesting insight into the special effects in '2012'. A *huge* surprise: they built part of their simulation software around Bullet - the open source physics simulation engine that's also part of Blender.
It's a great news for the Open Source community:
This challenge led DD [Digital Domain] to develop a new simulation system called Drop. "Our software team built it around a fast, open-source engine called Bullet," Leo says. "Bullet was the core solver, but we established a system for generating and breaking constraints and for assigning material properties to objects. That allowed us to do things that are very difficult for rigid body solvers, such as concave objects and organic shapes where collisions become very complicated. Drop is tremendously fast, and it allowed artists to iterate on a fairly long simulation in an hour or two. We were able to simulate tens of thousands of colliding objects.