Underneath the dollar signs of Wednesday’s Citrix acquisition of virtualization vendor XenSource, are the shifting motives of a complex web of vendor alliances aiming to provide corporate users with virtual environments and the tools needed to manage them.

With its $500 million acquisition of XenSource, Citrix cemented the evolution of its desktop tools via virtualization and established its intent to deliver server virtualization; XenSource, which will operate as a division of Citrix, now has the capital and sales channel to become a serious corporate alternative to VMware for server virtualization; and Microsoft – partner to both companies – may just have found the alliance to bridge the gap between its hypervisor vaporware this year and next year’s shipment of the real deal.

What users will get is a Citrix desktop virtualization environment and a number of options for deploying and managing virtualized servers on Windows. And they will see a determined effort from the Citrix/XenSource/Microsoft triumvirate to pool resources to battle VMware, which has nearly 85% of the virtualization market.

Corporate users, most notably Windows shops, will now have a legitimate alternative to VMware if they don’t want to wait for Microsoft to deliver its first-generation hypervisor technology in mid-2008.

In addition, Microsoft’s partnership with XenSource means users could opt for the Citrix/XenSource hypervisor now and migrate to the Windows Server Virtualization (WSV) hypervisor and Microsoft’s management tools when they ship.