I installed clean and setup up xen, but got errors: Error: Device 0 (vif) could not be connected. Hotplug scripts not working. found out that this is because hotplug is missing. "emerge hotplug" solved the problem. I don't know what the difference between hotplug-base and hotplug is but I'll figure you devs know. Keep up the good work.
Should be fixed in -r2. Thanks for your help.