Microsoft have released a new version of the the Live Mesh addin for Mac OS X that adds support for Lion. I used to be a big fan of the original Live Mesh product but was put off by the change in direction from the original vision and switched to Dropbox, I had forgotten that they even had a Mac version. If Microsoft developed an iOS version I would think of switching back.
Windows Live Mesh for Mac brings Live Mesh and the previous version of Windows Live Sync together into one product. With Windows Live Mesh for Mac, you can keep the folders you choose in sync across your computers (Mac and PC) so the files you need are always right there with you.