An April 7th, 2010 IDC opinion piece identified a key point of differentiation in enterprise operating systems that has emerged between the Linux and the Windows operating systems. The IDC report (1), available to IDC subscribers, notes the fact that Windows continues to announce that it will reduce its support for non x86 architectures. According to IDC program vice president, System Software Al Gillen, "Microsoft has been out-maneuvered by the Linux community, in that Linux today is available on every major architecture and processor, as well as a long list of processors and architectures that may not be considered to be "major." The report is available here where IDC subscriptions are available as well.
(1) IDC, Windows: Destined to Be a Monoplatform OS, Doc # lcUS22284310, April 7,2010