Six months ago, AMD and Havok were together at the Game Developers Conference demonstrating OpenCL-accelerated cloth physics. Today, AMD has announced another partnership with a different physics middleware developer: Pixelux Entertainment.
While not quite as widely used as Havok, Pixelux's middleware nevertheless found its way into LucasArts' Star Wars: The Force Unleashed. (According to GameSpot, LucasArts used Pixelux's Digital Molecular Matter for dynamically destructible environments and Havok's APIs for other physics effects.)
With AMD, Pixelux is pushing to make the open-source Bullet Physics middleware work with OpenCL. The move will allow physics simulations to run on any OpenCL-compatible graphics processor, meaning both Radeons and GeForces. AMD's press release even talks of compatibility with game consoles and "other hardware platforms." Pixelux will also make a version of Digital Molecular Matter that integrates with Bullet Physics.
Incidentally, AMD mentions that it's "actively pursuing support of Bullet Physics via the DirectCompute [programming interface]." DirectCompute is part of the DirectX 11 feature set, and like OpenCL, it lets developer tap compliant graphics processors for general-purpose computing. That said, the OpenCL folks claim Microsoft designed DirectCompute to work "within the context of the [DirectX] graphics pipeline," while OpenCL is a "standalone, complete compute solution."
AMD takes a shot at Nvidia's PhysX API in its announcement, stating, "Proprietary physics solutions divide consumers and [software vendors], while stifling true innovation; our competitors even develop code that they themselves admit will not work on hardware other than theirs." Indeed, PhysX works only on Nvidia graphics cards right now. Faced with competitive pressure from firms like Havok and Pixelux, however, Nvidia could conceivably port the API to OpenCL, DirectCompute, or both.