The open source Bullet physics library has SPU specific optimizations. Some of the SPU optimizations have been co-developed with Rockstar, for their GTA IV game.
Bindings for PS3 Linux, using libspe2 are included, as well SPURS, pthreads, Win32 threads and dummy 'sequential thread support' to make debugging easier.
Slides of a Game Developers Conference talk on SPU specific optimizations are available too:
http://www.bulletphysics.com/Bullet/wordpress/uncategorized/gdc-2008-physics-tutorial-on-parallel-game-physics-for-spu
More information: http://bulletphysics.com
Hope this helps,
Erwin