I've been a longtime fan of Groove, the peer-to-peer file sharing software invented by Ray Ozzie, also the creator of Lotus Notes and now Microsoft's Chief Software Architect.
Microsoft bought Groove and Ray came along with it--or rather, it bought Ray and Groove came along with him. He's been moving Microsoft in the director of cloud computing. It's about time and the next year should see lots of public results of those efforts.
I was also a fan of the little utility FolderShare which allowed peer-to-peer file sync between computers, including Macs and Windows. Microsoft bought that company too and it became Microsoft LiveSync.
The challenge with LiveSync and with the standard, small workgroup implementation of Groove is that peers have to have their computers on at the same in order to sync.
Microsoft has a new product in Beta called Mesh and it provides sync to the cloud and then back down to devices--Macs, Windows and Windows Mobile. Because of the cloud, peers don't need to be on at the same time. There's a light little app that installs on your desktop and provides a helpful little info window, including messaging updates. And Mesh will allow you to fully access your computer remotely from another computer, provided your computer has been left on and connected. Mesh looks like a winner.
I'm not sure where this leaves Groove. The extra security of Groove file sharing may no longer be enough of a value proposition. It will be interesting to see where this lands with Office 2010. Groove will be renamed "Sharepoint Workspace". News is supposed to be forthcoming soon, according to the Sharepoint Workspace Team Blog as of September 2, 2009.
(Two criticisms. First, Microsoft please, if you're in Beta with a product, the #1 news item on a Google or Bing search should not be an article from mid-2008! What is with your PR folks? Second, please, I can't stand the ads you guys run within products like MS Messenger and even within the Mesh Beta. Can't you drop those for the Beta? And I sure hope there's a for-fee option to get rid of those ads in the final Mesh. Messes badly with your nice and pretty interface.)