first of all congrats for the CentOS 5 release! I'm using on several production servers xfs as file system and would like to migrate them from CentOS 4.4/FCx to CentOS 5. I tried for a low priority image server the module downloaded from the site below:
http://dev.centos.org/centos/5/testing/SRPMS/xfs-kmod-0.3-2.2.6.18_8.1.1.el5...
This is the source package for the module. Is this the file you installed from or did you just not link correctly?