Nasa is using Bullet in their new open source Tensegrity Robotics Toolkit. You can find more information and video link here: http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=17&t=9978

The new book Multithreading for Visual Effects includes a chapter on the OpenCL optimizations for upcoming Bullet 3.x. Other chapters include multithreading development experiences from OpenSubDiv, Houdini, Pixar Presto and Dreamworks Fluids and LibEE. You can get it at the publisher AK Peters/CRC Press or at Amazon.

Development on upcoming Bullet 2.83 and Bullet 3.x is making good progress, hopefully an update follows soon.