Mailing the story:

Kernel Virtual Machine (KVM) virtualization has largely replaced Xen as the default open source mechanism for creating and supporting virtual machines (VMs) on most Linux systems. Though the motivation for this change is primarily build and support related rather than technical, the reality is that many enterprise IT groups that are interested in virtualization will need to learn the administrative command-and-control tools that KVM uses. Similarly, IT shops with an existing investment in Xen virtualization that are moving to KVM will probably want to convert existing VMs to the formats that KVM supports whenever possible, rather than having to re-create them.