HardenedBSD isn't some radical new BSD operating system but rather it's working on being a security-enhanced version of FreeBSD. HardenedBSD is just about providing security enhancements on top of the FreeBSD code-base. This initiative just started this summer by Oliver Pinter and Shawn Webb.
There isn't much to the HardenedBSD web-site besides their latest hardened builds based on FreeBSD. Ultimately though there might not be much to HardenedBSD if their work is successful as they hope to "upstream most, if not all, our projects" back into the FreeBSD code-base to improve its security.
Good luck to this new security-driven BSD effort!