AMD have just announced there will be a free version of the DMM engine. It sounds like it will be closely integrated with Bullet Physics and provide OpenCL support.
I'm looking forward to this as DMM is the only realtime finite-element (FEM) based physics engine around. I'm interested to see how well it works.
Hopefully I can get a copy soon and some time to integrate it into the Physics Abstraction Layer.
Here is a video of DMM to refresh your memory: