Bullet 3D Game Multiphysics Library

Bullet 3D Game Multiphysics Library provides state of the art collision detection, soft body and rigid body dynamics.

Used by many game companies in AAA titles on Playstation 3, XBox 360, Nintendo Wii and PC
Modular extendible C++ design with hot-swap of most components
Optimized back-ends with multi-threaded support for Playstation 3 Cell SPU and other platforms
Discrete and continuous collision detection (CCD)
Swept collision queries
Ray casting with custom collision filtering
Generic convex support (using GJK), capsule, cylinder, cone, sphere, box and non-convex triangle meshes.
Rigid body dynamics including constraint solvers, generic constraints, ragdolls, hinge, ball-socket
Support for constraint limits and motors
Soft body support including cloth, rope and deformable
Bullet is integrated into Blender 3D
Supports import and export into COLLADA 1.4 Physics format
Support for dynamic deformation of non-convex triangle meshes, by refitting the acceleration structures
The Library is free for commercial use and open source under the ZLib License.

Details and More Here --> http://code.google.com/p/bullet/

So is version 2.70 better than 2.67? That's the version I was working with before.