Virtualization

1. Xen
2. VMware
3. VirtualBox
4. KVM (Kernel-based Virtual Machine)

With ConVirt you configure, monitor and automate your Xen and KVM deployments and private clouds from a single at-a-glance dashboard. Open source virtualization is now a real option for enterprises!

Reference

1. http://www.convirture.com/

p.s. RHEL 6.0 Beta already remove Xen and may use KVM for virtualization.