Ageia PhysX 2.5 WHQL

Hardware/Software Rigid Bodies
Enhanced Rigid Body Sweep operation
Improved sleeping object/actor operation
Fine grain multi-threading
Greatly raised object and joint limits
Dynamic hardware acceleration management
Adaptive force improvements
Improved pulley and joints force propagation
Hardware Fluids
Improved SPH implementation
Fluids depth smoothing
Multiple fluid surfaces
User defined particles supported
Fluid interactions with rigid body.
Note: There are workarounds to get the same effect.
Hardware Cloth
Application control of stretching and bending resistance parameters
Advanced two way rigid body interaction with cloth
Attachments to cloth
Application controllable cloth damping and friction
Cloth tearing simulation
Cloth pressure simulation
Performance
Increased Hardware cloth & fluids
Faster sleeping objects processing
Reduced CPU impact of sleeping objected
New friction simulation
Narrow phase optimizations