Hyper-V, Microsoft’s virtualization technology, now supports CentOS Linux distribution. CentOS is actually community-supported, mainly free software operating system based on Red Hat Enterprise Linux (RHEL). It exists to provide a free enterprise class computing platform and strives to maintain 100% binary compatibility with its upstream distribution. CentOS stands for Community ENTerprise Operating System

Which versions are supported?
Hyper-V now supports following CentOS versions:

• CentOS 5.2 (x86,x64)
• CentOS 5.3 (x86,x64)
• CentOS 5.4 (x86,x64)
• CentOS 5.5 (x86,x64)
• CentOS 5.6 (x86,x64)

It is also good to know that Microsoft already supports Hyper-V environments that include Red Hat Enterprise Linux and Suse Linux Enterprise Server.

What does the support actually mean? Does it mean that I can’t run other Linux distributions on Hyper-V?

CentOS supported under Hyper-V

No, it actually means that you can run different Linux distributions, but they are not officially supported.  So for example if you try  OpenSuse, Fedora or Ubuntu under Hyper-V you’ll see that Hyper-V can run them also. So the difference is that Microsoft has thoroughly tested above mentioned distributions like CentOS, Red Hat Enterprise Linux while Fedora or some others are not tested and thus they’re not officially supported. Also it means that for supported distributions you can call up Microsoft Support and they will troubleshoot the problem. To conclude it isn’t  recommended to run unsupported distributions in your production because if some problems occur you’re stuck on your own without any support.