Amazon EC2 is a hyped technology that is actually exceeding it's expectations. It's cloud computing, and when Amazon added recent features to enable datacenter level fail-over and cluster tools, it became the best way to scale any large internet service.
It now has over 60,000 customers, some using thousands of instances of virtual hardware. Combined, they use more bandwidth than all of Amazon.com. Companies like RightScale are examples of a blossoming 3rd party support and service eco-system growing around EC2.
Google is attempting to do something similar with Google App Engine, and Sun and IBM have cloud models as well.
But Amazon EC2 doesn't do Windows. You can't run the Windows stack on it (at least in any real way). You can run Linux, FreeBSD, Solaris and almost any other Unix you can name. But no Windows. Windows is gonna fall further behind as the internet infrastructure shifts to cloud models.
Windows isn't Cloudy.