Almost 2 month ago NVIDIA relaesed version 2.61 of PhysX plug-in for 3ds Max (2009 – 2012, 32- and 64-bit). And already now they announce release of new version 2.7. Plug-in now features two different simulation engines – PhysX SDK 2.8.4 and new PhysX SDK 3.1, with an option to switch between them seemlesly, without necessity to restart 3ds Max. This new release is compatibility with other plug-ins that use PhysX directly (e.g. Thinking Particles) and also fixed some bugs, which are described in link at the end of this article.
2.7 PhysX plug-in for 3ds Max you can download through Developer Support Center.
Source: Physxinfo