Have you thought about adding a functionality similar to the EC2/Openstack Floating IP?
The existing OpenNeubla networking is already very flexible and powerful but the capability of mapping a public IP to a internal IP and quickly switch among VMs without any downtime is very powerful. This is already possible to implement at the user's VM level but the floating IP functionality would greatly simplify it.
I would imagine this to be implemented as an extra optional component similar to ozone or sunstone, thus no need to be part of the core oned service. The implementation would be straightforward with Linux virtual IPs + iptables rules.
I hope to see this feature in future releases.
Thank you very much.