I've built updated cfengine 2.2.6 packages for el4 and el5. You can find them in the usual spot:
http://sheltren.com/downloads/cfengine/testing/
The same package has been built for Fedora development/rawhide and should be available there soon.
Some bug fixes as well as support for detecting xen hosts/guests is now included. Let me know if you have any problems!