NetBSD/xen is a port of NetBSD to the Xen virtual machine monitor. It was first brought to NetBSD by Christian Limpach and committed to the source tree on March 11th, 2004.
Xen is a virtual machine monitor for x86 that supports execution of multiple guest operating systems with unprecedented levels of performance and resource isolation. Xen is Open Source software.
See http://www.xen.org/ for more details on Xen.
The current maintainer of NetBSD/xen is Manuel Bouyer.