This is release is part an update and part a new release.
Demo 4 and 5 of this release are the same as the previous 1 and 2 demos, but updated for the new XNA Beta 2.
Demo 6 in this release shows off some new Joint functionality in the engine.
There misc other updates to the Physics engine, but I will not list them here. I will be doing a more formal release sometime in the near future.