CFS is a way of encrypting an entire directory trees and allowing users to store encrypted files on them. It uses a NFS server running on the local machine. RPMS are available at http://www.replay.com/redhat/, and more information on how it all works is at ftp://ftp.research.att.com/dist/mab/.
TCFS improves on CFS by adding more integration with the file system, so that it's transparent to users that the file system that is encrypted. more information at: http://edu-gw.dia.unisa.it/tcfs/.
It also need not be used on entire filesystems. It works on directories trees as well.