I have been setting up Xen based virtualization and I just wanted to post the useful links I have found. Unfortunately (at the time of this writing) there are couple of bugs in the Ubuntu repositories for Xen that can make installing and configuring Xen a bit of a headache.

This article on HowtoForge pretty much gives you everything your need to get going (even how to get around the current bugs).

http://www.howtoforge.com/ubuntu-8.04-server-install-xen-from-ubuntu-repositories

This is the user manual for Xen. Unfortunately it is not very descriptive in places, but it is still a good resource.

http://tx.downloads.xensource.com/downloads/docs/user

This is the manual page for xen-create-image. It has some really great examples to base your DomU creation commands from.

http://man.cx/xen-create-image

Below is the Ubuntu community documentation for Xen. They still need some time to update to Hardy.

https://help.ubuntu.com/community/Xen