Faye and Russell Coker's article “Taking advantage of SELinux in Red Hat Enterprise Linux”: www.redhat.com/magazine/006apr05/features/selinux
McCarty, Bill. SELinux: NSA's Open Source Security Enhanced Linux. Sebastopol, CA: O'Reilly Media, 2005. Definitive resource, but predates Red Hat and Fedora's implementation of “targeted” and “strict” policies.
Mayer, Frank, Karl MacMillan, and David Caplan. SELinux by Example: Using Security Enhanced Linux. Upper Saddle River, NJ: Prentice Hall, 2007. Brand new book, by several SELinux contributors.
“An Overview of Object Classes and Permissions”, from Tresys Technology: www.tresys.com/selinux/obj_perms_help
“Red Hat Enterprise Linux 4: Red Hat SELinux Guide”: www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/selinux-guide/index.html
Mayank Sharma's article “SELinux: Playing with fire”: security.linux.com/security/05/01/25/1423211.shtml?tid=124&tid=123&tid=113&tid=35
Mick Bauer's “Linux Filesystem Security, Part I”: /article/7667
Mick Bauer's “Linux Filesystem Security, Part II”: /article/7727