This is a guest post from Larry Dignan of TechRepublic’s sister site ZDNet. You can follow Larry on his ZDNet blog Between the Lines (or subscribe to the RSS feed).

Citrix on Feb. 23 will detail plans to offer free licenses to its XenServer virtualization application and team with Microsoft to swap support. Citrix and Microsoft will also extend their 20-year partnership into the virtualization market.

In a nutshell, Citrix will work with Microsoft to provide system management, Citrix Essentials for Hyper-V. Microsoft’s System Center will support XenServer.

Steven Vaughn-Nichols detailed the Citrix plans on his personal blog. Apparently Citrix briefed a bevy of bloggers about its plan under embargo, but the presentation is flying around in various in-boxes. Vaughn-Nichols notes that Citrix won’t open source XenServer, however.

Add it up though and it’s clear that rivals of VMware–Microsoft, Citrix and Red Hat–are all cutting deals to gang up on the leading virtualization player. Earlier this week Red Hat and Microsoft teamed up on an interoperability pact.

Vaughn-Nichols also notes another interesting thread:

It’s also expected that at least one of the two major Linux companies, Novell or Red Hat, will announce their support for the new XenServer and Citrix Essentials for XenServer. It is not known, however, which of the companies will be making this jump.

Citrix’s presentation offers further details. I received the presentation in my inbox from two different sources.

This slide highlights Citrix’s big plan–along with Microsoft and Red Hat for that matter. The gist: Blow up the pricing models.

Use Microsoft’s clout to piggy back on mixed source implementations. This goes back to the frenemy argument. Open source virtualization players are more than happy to work with Microsoft to thwart VMware.