SELinux
The SELinux policy in Fedora 7 has the neccessary rules to allow use of Xen with SELinux enabled. The main caveat to be aware of is that any file backed disk images need to be in a special directory - /var/lib/xen/images. This applies both to regular disk images, and ISO images. Block device backed disks are already labelled correctly to allow them to pass SELinux checks.