SELinux is a Linux distrubution focused on security issues. It is worked on by the NSA, an american government security agency.
Throwing some notes in for now...
http://www.lurking-grue.org/gettingstarted_newselinuxHOWTO.html
http://www.coker.com.au/selinux
http://selinux.lemuria.org/install-2.6.html
3 pages link to SELinux:
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