According to this page on Microsoft’s Live Mesh site, the Mac version is now ready for download. It reads that with the Live Mesh Mac extender, you can
Add your Mac to your Live Mesh - it will appear with your other devices on www.mesh.com
and throughout the Live Mesh UI.
Synchronize files between your Mac, your other computers, and your Live Desktop.
Synchronize folder contents between your Mac and other folder members.
Easily access Live Mesh news, your Live Desktop, and manage your devices from the Live Mesh menu bar item.
Receive notifications through Live Mesh when updates are available and easily update the Live Mesh extender for Mac.
But, be warned, the Mac version is still under development, so there may be issues with it.
Gratis (è una tech preview quindi rilasciate feedback piu che potete)