It seems as though the guys over at PC-BSD will soon be officially offering a rolling release of their OS very soon.
Right now, there is a test image available for all those who want to try it out.
http://www.freebsdnews.net/2013/02/2...lling-release/

They've also explicitly stated that they will not be moving onto a rolling release model, they'll just be offering it as an option beside the standard stable releases.