Hello,
I just wrote a step-by-step tutorial how to install the latest Xen 4.0.1 hypervisor on Fedora 13 (x86_64) host from src.rpm packages, and the pvops dom0 kernel from git repository.
Check it out: http://wiki.xensource.com/xenwiki/Fedora13Xen4Tutorial
It also shows how to install various Xen PV guests using the native distro installers:
- CentOS 5.5 - Fedora 13 - Ubuntu 10.04 LTS
Hopefully this is helpful to someone! :)
-- Pasi