The Windows Azure Platform is currently based on a modified version of Windows Server 2008 R2. The Windows Azure philosophy is for Microsoft to take care of all the infrastructure requirements and let you focus on solving your business problem.
One requirement that has had customers curious is how we will handle the issue of operating system versioning, in other words, do they automatically have to have their application run under a recently upgraded or patched version of the OS without their approval?
Now we have an answer. With the addition of a new Service Configuration file parameter osVersion, you can now specify the version of the OS that you want your application to run under. This is similar to the way we handle .NET Framework versioning in Visual Studio. As you may recall you can specify the version of the .NET Framework that you want your application to run with at compile time in Visual Studio.
We currently have only one version listed as being available, but there will be more as time goes on.