"vmbuilder is a tool (introduced on Ubuntu 8.10) that allows you
to build virtual machines (with Ubuntu as the OS) for multiple
virtualization techniques. Currently it supports Xen, KVM, VMware
Workstation 6, and VMware Server. You can afterwards copy the
virtual machines to another system (a Xen, KVM, VMware Workstation
6, or VMware Server host) and run them there."