"Microsoft said it is now adding interoperability
support for CentOS Linux so it can be run on Hyper-V, the
virtualization platform that comes with Windows Server. There's a
healthy does of self-interest here, as Microsoft is trying to
improve the viability of Hyper-V in an all-out war to topple VMware
from its place at the top of the virtualization market, while also
fending off open source competitors Xen and KVM.
"Plus, Linux is widely used in the Web server market. But you
also might call supporting CentOS an indirect compliment paid to
rival Red Hat, because CentOS is a version of Linux based on the
Red Hat OS."