|Official website: http://bulletphysics.org|
|Bullet on WikiPedia - http://en.wikipedia.org/wiki/Bullet_(software)|
Being an open source physics library, there has been plugins written for many 3D animation packages based on the engine. These include major packages like Maya, 3D Studio Max, Softimage, Cinema 4D, Lightwave and Blender.
In addition, many plugins are also making use of the computational power of gaming and professional display cards to speed up the performance of their plugins with hardware acceleration.
Bullet has been used in the creation of next generation games, TV content and films including animated films like Bolt, Megamind, How to Train Your Dragon and Shrek.
There a plugin for Maya and Max called Dynamica. This is also open-source, also created by Disney Animation, available for download at the Bullet Physics Project page.
After installing the plugin, there are videos linked to their document page that an visually demonstrate how to configure and set up a scene using Bullet.
I've downloaded, but have not tried it yet.
I'll post personal tests when I start playing around with it and creating stuff with the tools.