ports has already had this for some time:
http://svnweb.freebsd.org/ports/branches/
There might be semi-official repos for those somewhere as well. Or you can always build your own with poudriere.
> Coming from Debian, I long for a similar model in FreeBSD.
Oh hell no. This gives silly issues like Lenny's pigz being broken for like 4 years. Or OpenSuse's crappy model which shipped a shitty version of kde4 long after it had become stable elsewhere.