One of the anomalies of the currently-fashionable cloud computing is that people tend not to talk about the underlying operating system – presumably because they tend to think the cloud *is* the operating system.
The fact is that both of the main cloud computing systems – from Amazon and Google – have been running on GNU/Linux. In other words, not only is open source running vast swathes of the Internet, but now it's holding up nearly all the clouds, too.
Actually, that was the situation until 23 October, when Amazon announced that it would be adding cloudified Windows Server alongside GNU/Linux:
Amazon EC2 running Microsoft Windows Server 2003 is a fast and dependable environment for deploying applications using the Microsoft Web Platform, including ASP.NET, ASP.NET AJAX, Silverlight, and Internet Information Server (IIS). Amazon EC2 enables you to run any compatible Windows-based solution on AWS’ high-performance, reliable, cost-effective, cloud computing platform.
Common Windows use cases include website and web-service hosting, high-performance computing (HPC) and data processing, media transcoding, distributed testing, ASP.NET application hosting, and any other application requiring Windows software. Amazon EC2 also now supports the SQL Server Express and SQL Server Standard databases, and makes those offerings available to customers on an hourly basis.
Using Amazon EC2 with Windows Server is similar to using Amazon EC2 with any other operating system. Amazon EC2 running Windows will provide seamless integration with existing Amazon EC2 features like Amazon Elastic Block Store (EBS) and Elastic Ips.
Amazon's decision to launch at this time was doubtless driven by the knowledge that Microsoft was about to unveil its own cloud computing initiative, which finally turned up this week: