Well, I didn’t see this one coming. It appears that Citrix is about to open-source XenServer. There are few details so far, but I’d expect that what they are open-sourcing are the server-side components — IE, their management framework for Xen. I’d be surprised if they open-sourced their .Net XenServer client, but by open sourcing the server side of the stack, I wouldn’t be surprised to see other clients pop up. (The client apparently is purely API-based — IE, it doesn’t have any special access to xapi that other API consumers wouldn’t have.) I’d love to see a OS-independent client pop up. ;)
In any case, I’m glad to see this, and look forward to playing with the bits!