This is not a help page. For help with Xen, go here https://help.ubuntu.com/community/Xen .
This page is dedicated to developers co-ordinating how xen is to be setup in Ubuntu, and how the default configuration should be.
I set this page up because I wish there was a way to get involved in the larger Ubuntu Xen community. I can't even figure out how to get Xen working on Gutsty Server AMD64. So far all I have figured out is apt-get install linux-xen, but this only appears to be the kernel. I don't know why the AMD64 and 386 versions of ubuntu have such different xen packages.
Ubuntu Xen Team on launchpad here: https://bugs.launchpad.net/~ubuntu-xen/