Through lots of hard work by Manuel Bouyer full Xen3 support is now available in NetBSD. Xen3 DomU support has been functional in NetBSD since the end of March, but this added functionality now makes it possible to run a controlling or privileged Xen3 domain under NetBSD as well. Please see Manuel’s
email to the port-xen mailinglist as well as the NetBSD/xen website for further details.
Please note that dom0 support for Xen3 is only available in NetBSD-current atm. The 4.0 release will have it. Xen3 domU support however has been backported to the netbsd-3 branch and will be available in NetBSD 3.1.
Support for Xen2 (both dom0 and domU) has been available in 3.0 for a while now.