I'v seen that thread too,but it's kind a old,a lot of version changes since then.Does that kvm supports things like bandwidth monitor/limiting,ip assign,cpu nodes,etc..
post is old but it works, regarding kvm i did not know any opensource tool. its better to made your own script for that about KVM you can reach. I have setup my own KVM base server and guest by manual and for monitoring use our own script not open source.
LOL, KVM and Xen are not even on the same playing field. BY far most of Xen's implementations are using paravirtualizatoin and xen is used in a corporate environment, versus kvm which is very young, slow corporate adoption (practically none), and very minimal paravirtualization. While kvm can be an alternative to xen, not in most cases. And, as Norman pointed out, custom tools need to be created for it in many cases to many things that xen already has available. To say that xen is dead and old is absurd.