Citrix have open sourced their recently acquired cloud management platform 'Cloudstack'. It apparently supports multiple hypervisors: Xen, KVM, Vmware ESXi
The install guide is worth a read even if you're not considering installing it as it goes over some 'best practice' config for storage, networking setup etc.
http://download.cloud.com/releases/2.2.0/CloudStack2.2.9InstallGuide.pdf
Just wondering if anyone has any experience with it?
- Ian