NSA research prototype made public, has modified kernel, several utilities; has enhanced security-related functions designed to show value of mandatory access controls and how such can be added to Linux; not a full OS distribution. http://www.nsa.gov/selinux/
Openwall GNU/*/Linux is a server distribution; main means to security: proactive source code review, privilege separation; several other means also used. Available for use. English, French, German, Russian. http://www.openwall.com/Owl/
Server distribution, goal: provide level of security needed to create corporate web presence or conduct business on Web. Security achieved via included software and using principle of least privilege; available for use. http://www.engardelinux.org/
Appliance-based special-purpose hardened Linux distribution with firewall, VPN, anti-virus functionality. Some functionality is available for free for home use, the rest is commercial. http://www.astaro.com
Small CD-based distribution used for firewalls, routers. System configuration settings are stored on separate floppy disk. Descriptions, news, documents, downloads, links. http://www.devil-linux.org/
Server platform, Red Hat based, hardened against several classes of attacks via using Immunix tool family which includes StackGuard compiler, FormatGuard, SubDomain. Available for use. http://www.immunix.org/
Server distribution from ALT Linux Team. Improved security is achieved with the use of RSBAC, general privilege separation approaches, and certain pieces and ideas from Owl. A beta is available for testing and use. http://castle.altlinux.ru