Buried under the buzz around Windows 7 RC release, here’s an important update from Microsoft - Windows Server 2008 R2 release candidate.

Windows Server 2008 R2 is the first Windows operating system to be offered for only 64-bit processors. And Windows Server 2008 R2 can now support up to 256 logical processor cores for a single operating system instance, including enhancements in Hyper-V virtual machines which are able to address up to 32 logical cores in a single VM. These improvements not only guarantee more bang for your server hardware buck, but also offer better reliability with fewer locks and greater parallelism.

Regarding virtualization, Windows Server 2008 R2 provides the following virtualization types: Client and Server virtualization provided by Hyper-V and Presentation virtualization with Remote Desktop Services. Hyper-V virtualizes the system resources of a physical computer allowing you to provide a virtualized environment for operating systems and applications.

If you want to build your own cloud, this is the OS you want to use.

You can download it here.