The Linux Foundation has taken control of the open source Xen virtualization platform and enlisted a dozen industry giants in a quest to be the leading software for building cloud networks.

The 10-year-old Xen hypervisor was formerly a community project sponsored by Citrix, much as the Fedora operating system is a community project sponsored by Red Hat. Citrix was looking to place Xen into a vendor-neutral organization, however, and the Linux Foundation move was announced today. The list of companies that will "contribute to and guide the Xen Project" is impressive, including Amazon Web Services, AMD, Bromium, Calxeda, CA Technologies, Cisco, Citrix, Google, Intel, Oracle, Samsung, and Verizon.

Amazon is perhaps the most significant name on that list in regard to Xen. The Amazon Elastic Compute Cloud is likely the most widely used public infrastructure-as-a-service (IaaS) cloud, and it is built on Xen virtualization. Rackspace's public cloud also uses Xen. Linux Foundation Executive Director Jim Zemlin noted in his blog that Xen "is being deployed in public IaaS environments by some of the world's largest companies."

Xen is thus a threat to VMware in its quest to evolve from a virtualization vendor into a cloud vendor. Xen is even complementary to OpenStack, the popular open source cloud infrastructure software that can be used by either private businesses or service providers to build IaaS clouds. Xen is one of several hypervisors that can be used with OpenStack.

But Xen isn't the only open source virtualization contender. KVM (Kernel-based Virtual Machine) can also be used with OpenStack, is part of the Linux kernel, and is financially backed by Red Hat.

Linux's embrace of Xen does not spell the end of KVM in Linux, Zemlin wrote. "The market has proven there is opportunity for more than one way to enable virtualization in Linux, and both KVM and Xen have their own merits for different use cases," he noted. Xen is inching closer to the Linux kernel, however. "[T]he Xen Project has adopted mainline kernel development practices and is progressing ever closer to the mainline kernel community," Zemlin wrote. Already, "Linux can run unmodified as a Xen host or guest."

Citrix is not giving up on Xen, saying that it "will remain committed to the project and advancing the technology for Xen Project-based products across the industry, including its own Citrix XenServer.”