Ray Ozzie has spoken a lot about the Mesh in the last few years - the groups you might belong to that have members that don't belong to your organization or work behind your firewall. He recently hinted at something tangible that brings synch to a much broader range of devices. Live Mesh, announced by Microsoft yesterday, addresses some business team needs (but not all) and some more needs not satisfied by anything (most if not all of my devices). Live Mesh synchronises files amongst your devices and if you choose, others' devices. Plus it allows you to work more flexibly with your other devices and their apps through a browser.
But it's not a rich collaborative environment. If you have a project where you wanted to capture all of a team's interactions in one spot, Live Mesh as it stands wouldn't be sufficient. It doesn't have Groove's robust, always on security capabilities. Nor does it compartmentalize a group's interactions the way Groove does, making it much easier to track progress - or at least I didn't see it that way. Because if it did, it would provide a great tool for small business project collaboration.
Here's a good overview http://on10.net/