I have implementation of trustedos based on trustedbsd sources (mac, audit2)
and my own development applied to FreeBSD-5.3. It includes CIPSO/IPSec packet
labeling, audit2,3+apple based BSM audit with my own daemon, semi-hacked
library and utilities. Plus some bugfixes (MAC NFS, audit tailq panics, maybe
something else). Look for trustedos.tbz in download dir.
A list of my favorite links:
FreeBSD POSIX.1E implementation