Why not just use KVM and oVirt?
Seriously, what's the point of this project? XenServer has an extremely limited hardware compatibility list, a weak feature set, and no real third-party support. At best you could say that it is has a few niche historical uses.
Given the complexity of the features that aren't in the XenServer Free version (anyone care to implement NVidia and AMD GPU virtualization support this weekend?), I doubt that this will be a long term success, although you could say "emergency stop-gap".
If all they are trying to achieve is to resurrect the management APIs of XenServer, they're better off just adding any missing bits to libvirt.
People need to wake up and smell the coffee. It's good coffee, and available free now in CentOS.