I've been using Live Mesh on my Windows PC for a little while now and I absolutely love it. I've found Mesh to be really for backing up personal files like photo's and sharing work with colleagues who also use Mesh. It's just gone into full beta with tech previews of Windows Mobile and OS X clients.
Features include on-line file backup, cross platform compatibility (XP, Vista, OS X, Windows Mobile 6 & 6.1), remote control of other PCs in your own mesh, and the ability to share folders with other users. It's a really solid service for something that has just gone into beta. I particularly like the background synchronisation of files between the devices in your mesh. Also, I have a Windows Mobile phone and a Mac, so it's like the service was built for me. I really recommend you take a look at mesh.com for more information.