LinuxWorld article (4 pages)
here.
A security framework originally published by the US National Security Agency has begun to rack up an impressive list of protections agains security holes.
-- Tom
P.S. Some folks get paranoid when NSA is mentioned. There is no reason for this with regard to SELinux software when you can get the finer grain of blocking security that it offers after you get compromised and it stops the worst that can happen from happening - for example, if the root account has been compromised by malware, it can policy block changing the root password - see article for more.
Note: I checked my own Ubuntu Live CD (7.10) Gutsy Gibbon and there are some installed SELinux libs, not all of the tools, but enough to consider installing the entire set.