Just two weeks ago Microsoft officially launched its new Server Virtualization Validation Program (SVVP), developed to extend the support to those 3rd party hypervisors that pass validation.
At the announcement time a number of key virtualization vendors already applied for the Program, including Citrix, Novell, Sun, Virtual Iron and Cisco (why Cisco?).
At the last minute VMware confirmed its commitment and now, ironically enough, its flagship hypervisor, ESX 3.5 Update 2, is the first to pass the validation.
This means that from now on, Microsoft had to deliver cooperative technical support to those VMware customers running Windows Server 2008 and earlier, as well as any Microsoft back-end server defined in the program (and this includes mission critical products like SQL Server and Exchange).