Operating system versioning in Windows Azure
A new interesting feature ,you can now choose when your applications will receive operating system updates and patches by selecting which version of the operating system your applications will run on in Windows Azure.
This feature allows you to test your application before upgrading your production deployment.
To select an operating system version for your application, add the new osVersion attribute to your service configuration file. The full list of available operating system versions is maintained in the Configuring Operating System Versions topic in the Windows Azure MSDN documentation.