I never thought it would happen, even when Sun Microsystems started selling Intel based workstations and servers along with their SPARC based systems, but it has. By the end of the year, Sun will start selling its 64-bit x86-based servers with Windows Server preinstalled instead of Solaris.
As part of the deal, Sun will cooperate on technical development of Windows Server on the Sun Fire hardware and will also work to make Solaris fully manageable under Microsoft's System Center Virtual Machine Manager.