Xen:
Xen Projecks
Xen hypervisor
Xen Cloud Platform
Xen ARM
RHEL5.3 Xen
RHEL5.4 Xen and KVM (64bit)
RHEL6.0 KVM (64bits)
RHEL6.0 DomU, but can not run as Dom0
Linux: 2.6.37 (3.0+) you can start running Dom0
Xen-4.0
xend / XM
Xen-4.1
XL, xend / XM
Xen-4.2
XL
Xen virtualization architecture system: 
running Dom0 configuration requirements: 
run DomU configuration requirements: 
xEND Xen hypervisor
XAPI Xen Cloud Platform
libvirt
libvirtd/virsh
virt-manager：GUI
virt-install
Third-party platform:
OpenStack
CloudStack
OpenNebular
KVM/Qemu --> Virsh , qemu-kvm