I've been using Proxmox VE for about a year as well as CloudStack and Virtualbox, but I recent came across something quite new to me. Archipel Project, anyone use this? I'm really considering this to try out and see how I like it. It's quite different in that it talks over a XMPP server, the admin can even "chat" to the VMs and ask how they're doing. I'll post my thoughts when I get a few hours to test this out. I can't post links, but if you search for Archipel Project, it's the first link.