Trust in the NSA, Luke!
The NSA has a free distro of linux entitled, 'seLinux'. as of the 2nd of this month they updated the kernel to 2.5.10 along with added some extra technical manuals and white papers. I may have to download it and try it out, though I would be interested in knowing what the more *nix profecient HITB members think about it. Check it out here.
