You can also see a recent interview with David Treadwell.
http://www.techcrunch.com/2008/04/27/just-say-yes/"Treadwell: I see your point. That’s one of the things we know we have to do a good job with Mesh; that is, to be IT-friendly, and to give IT control on what kinds of data can and can’t be stored on this thing. In addition, one of the things that we expect to do longer-term is to allow IT departments to operate their own cloud storage mechanisms, such that data owned by that enterprise would only be stored on that enterprise’s devices and that enterprise’s servers. They would never go to Microsoft and they would have complete control of that data."
So it seems it's a future plan but who knows what kind of infrastructure you'll need to support your own cloud.
