LWN.net: "Once upon a time, Xen was the hot virtualization story. The Xen developers had a working solution for Linux - using free software - well ahead of anybody else, and Xen looked like the future of virtualization on Linux. Much venture capital chased after that story, and distributors raced to be the first to offer Xen-based virtualization. But, along the way, Xen seemed to get lost."