Oracle XEN VM Server

http://wiki.oracle.com/page/Oracle+VM

Oracle VM is free server virtualization software from Oracle that supports Oracle and non-Oracle applications. Oracle VM offers scalable, low-cost server virtualization. Both Linux and Windows guests are supported. (See FAQ.) Consisting of Xen's open source server software and an integrated Web browser-based management console, Oracle VM provides an easy-to-use graphical interface for creating and managing virtual server pools, running on x86 and x86-64-based systems, across an enterprise.