Lookie what I found!
http://www.nsa.gov/ia/_files/os/redhat/rhel5-guide-i731.pdf
A 170 page PDF about securely configuring Red Hat, written by and for
the government. If you look around on NSA.gov, you'll find similar
things for OS X, Solaris, and even Windows.
Cool stuff, I think. Who ever thought of looking to the government for
security tips? :P