Here is an article from the NY Times today which has a doodle from Steve Ballmer which outlines the Microsoft Cloud Platform. You can see the full article here.

http://bits.blogs.nytimes.com/2009/03/20/steve-ballmer-maps-microsofts-cloud-y-future/

The general view is that this is not that complicated. Its Windows Server, SQLServer, our dev tools and a clear identity strategy, all running at scale.