Sun xVM is a free open source virtualization platform

Sun xVM.

xVM is a free, open source virtualization platform, which was unveiled at Oracle Open World, alongside our management platform, xVM Ops Center.

xVM will virtualize Windoz, Linux or Solaris, on either Dell, HP, IBM or Sun hardware.

http://blogs.sun.com/jonathan/

xVM is based on the work of the Xen community. In a running system, Xen fits between the hardware and the operating system.

http://opensolaris.org/os/community/xen/docs/developers/