libvirt is "A toolkit to interact with the virtualization capabilities of recent versions of Linux (and other OSes)." Basically it provides a programmer with a stable API to manipulate virtual machines based on KVM, Qemu, Xen, Virtualbox, and several other virtualization systems. See http://libvirt.org for more details. The latest release of libvirt - 0.8.7 - now contains full support for IPv6 on its "virtual networks", which are used to connect virtual machines to each other via a local subnet that is then routed to the physical network through the virtualization host's IP stack. Real-life testing of this new feature would not have been possible without the services provided by SixXS, and I would like to thank them for that. Laine Stump libvirt development team