Later today, Microsoft will make a virtualisation-related announcement. It seems likely that our assessment was correct [1, 2, 3]. Citrix grabbing XenSource was potentially a maneuver that simply advanced Windows without getting Microsoft in too much trouble with the FTC and the GPL. Moreover, it seems possible that Microsoft will acquire Citrix some day, as the following revealing article from Forbes suggests (published just moments ago).

Microsoft announced that it competed acquisituion of Calista Technologies, a San Jose, Calif.-based start-up that makes computer graphics for virtualized computers, and an expanded partnership with Citrix Systems, a VMware competitor based in Fort Lauderdale, Fla. Microsoft and Citrix will jointly market services that "virtualize" computers, operating systems and applications.

Microsoft's shot across the bow at VMware is inevitable as companies throughout industry shift to Web-based services. "Microsoft needs to get something into the market quickly," says Roger Kay, president of technology research firm Endpoint Technologies Associate. "Windows Office has 10 years to burn, but it will become less relevant."

[...]

A Microsoft-Citrix combination could present formidable competition to VMware, he suggests. Buying Citrix, however, would be a significant deal: The company has a market capitalization of $6.4 billion.

It would be safer to wait and see what Microsoft has to say. XenSource and Novell have a certain similarity in the sense that Microsoft can (and probably will) bend them both in Windows' favour. Microsoft executives are already deep inside XenSource and some announcements previously made seemed to suggest that Linux isn't a strategic priority as high as it used to be. Consider this another case of using money to divide and leverage Windows through deals and acquisitions. ⬆

Update (22/01/07): The announcement was made hours ago and it only confirms the fact that Microsoft uses Citrix (Xen, by association) to assist its own fight against VMWare.

Citrix is developing a software tool that helps Microsoft's Hyper-V virtualization feature in the upcoming Windows Server 2008 to work more easily with Citrix's XenServer product.

[...]

Microsoft has acquired a start-up company called Calista Technologies and expanded its alliance with Citrix Systems, targeting VMware's early lead in virtualization technology.