When Sun and Microsoft announced their initial rapprochement in April 2004, the long-time adversaries couldn't quite bring themselves to use the word “agreement,” much less “partnership”, to describe the deal.

Instead, they characterised their decision to pursue interoperability between the Java and .NET environments and between their respective directory services as “a broad technology collaboration arrangement”. The fact that Sun and Microsoft are now promoting their current news as an expansion of their 'strategic alliance' shows just how much the world has changed in the intervening three and a half years.

Sun's decision to become a Windows Server original equipment manufacturer (OEM) at this point is merely a natural progression for the company, which certified Windows for use on its servers a while back. Now customers can have Sun pre-install Windows Server 2003 on x64 servers prior to shipment, rather than loading it themselves or having a Sun channel partner do it for them.

Sun wouldn't commit to OEMing Windows Server 2008 when it ships, but it seems a forgone conclusion that the vendor will do so. Now that Sun has become the last major systems vendor to OEM Windows, it isn't likely to backslide to its former position once the next-generation of the Windows OS ships next year.”

Sun and Microsoft's decision to focus on virtualisation as a key part of their expanded alliance reflects the strategic importance both of these vendors' place on this technology - as well as growing customer demand for it.

Under the new agreement, the two will ensure that Sun's Solaris OS runs well on Microsoft's virtualisation technologies (including the current Virtual Server, and the future 'Viridian' hypervisor platform) and that Windows runs well on Solaris's virtualisation technologies. (Solaris's virtualisation capabilities are considerable.)

Work on this interoperability will constitute a major part of the activity at the Redmond-based Interoperability Lab, along with proof-of-concepts, benchmarks, and other work done to test specific customer-driven projects.”

Sun and Microsoft's virtualisation collaboration is just the latest in such vendor-to-vendor partnerships in this still-nascent marketplace. For example, Microsoft also has separate virtualisation alliances with Novell and with Citrix Systems.

With their limited agreement in this area, both Sun and Microsoft seem to be keeping their options open with regard to future virtualisation moves. Sun, for instance, won't commit to supporting Microsoft's Virtual Hard Disk (VHD) file format, and Microsoft is resisting moving all of its point-to-point virtualisation relationships under a common umbrella.”

The two companies talked about a 'wide-ranging go-to-market effort' under which they will promote various combinations of Sun's hardware and Microsoft's software. The only specific example of such a pairing, however, is one in which the two are supplying AT&T's U-verse digital TV offering with Sun servers running Microsoft's Mediaroom IPTV offering.”

As with the original 'arrangement' between Sun and Microsoft, this latest collaboration reflects the demands of the company's joint customers, the increasing pragmatism of the vendor's respective leadership teams, and the growing maturity of the IT marketplace.

The pitched battles between Microsoft and Sun in the past were great spectator sport, but not very useful for their mutual customers. With Sun noting that 100% of its Solaris customers use Windows, it only makes sense for the two vendors to ramp up their cooperation on some fronts, even as they continue to battle one another across a wide range of products and markets.”

Dwight B. Davis is Vice President at Ovum Summit