OpenNebula – The Engine for Data Center Virtualization & Cloud Solutions
http://www.opennebula.org/doku.php

OpenNebula is an open source virtual infrastructure engine that enables the dynamic deployment and re-placement of virtual machines on a pool of physical resources. ONE (OpenNebula) extends the benefits of virtualization platforms from a single physical resource to a pool of resources, decoupling the server not only from the physical infrastructure but also from the physical location. This has been added to Grid Resources Subject Tracer™ Information Blog.