For those doing native application development that need a Physics or Animation product, Havok, partnered with Intel have released the world famous Havok Physics & Animation package for free.

This gives you the complete binary for use in your personal, educational or even commercial game as long as it is below US$10.

Currently there does not seem to be anything for XNA (despite an apparent job ad a while back), but I am sure this will be wrapped soon enough, and then the power of Havok will be available for use on the PC platform in XNA as well.

You can get Havok from http://tryhavok.intel.com. Just fill out the form and download the Programmer binaries and Artist tools.