What the heck is a "cloud OS" anyway? If it's just a set of software that lets users and application service providers build Web-based services, Microsoft already has that. Combine Windows Server 2008 with ASP.NET and the Windows Communication Foundation and you're pretty darned close. Is it possible that Strata is primarily a repackaging and reorganization of existing Microsoft technologies and initiatives?
No, that wouldn't be grand enough. Strata is another, er, stratum on top of all of that existing stuff. A couple of years ago, there were some noises about something called Live Core that was to be Microsoft's cloud OS. The same people involved in that effort have been associated with Live Mesh, Microsoft's still-embryonic file and data synchronization technology. So this announcement will reveal some more components meant to interact with Live Mesh, ones that may not be available to users for several years.
This seems like the paradox of "cloud OS" hype. If Windows Strata is a new take on existing Microsoft products and services, combined with some strategic glue, it could be useful to Microsoft customers in the near term but probably not worthy of too much excitement. If Strata is a bold vision of the distant future -- filled with Swiss-cheese-like holes to be plugged by new, unwritten, and untested Microsoft technologies -- it will be covered excitedly in the press but have very little practical impact to customers for a long time to come. I would prefer the former, because we don't need another Hailstorm.