Hey,
I'm participating in the Uru beta test as part of Gametap. Originally, we did not get a Mac port of Uru because it used Havok. However, this seems to have changed. The newest beta uses AGEIA PhysX instead of Havok.
The change in physics engine would seem to imply that they are working on a Mac version, given that the physics engine was the only thing holding the game back, and there has to be a good reason behind the change in physics engine. Havok isn't exactly broken or anything.