Yesterday I deprecated the non-default Fedora based Linux base ports. This means fc6, f7, f8 and f9 will vanish soon (I decided for one month of expiry time). This is because all of them are End of Life upstream since a long time (= no security updates).
The fc4 and f10 ones are still available – even if they are End of Life too – because FreeBSD 7.x can not use something newer than the fc4 one, and we have not tested yet a more recent Linux distribution.
Probably the most easy way to update the Linux base ports to something newer is to stay with Fedora (we have a lot of ports-infrastructure for it already). Unfortunately it is not known if something newer works without problems (missing epoll/inotify support could be a roadblock here in case it is extensively used in a more recent version).
I want to get some time to have a look if a more recent Fedora version is suitable for the use as a Linux base in FreeBSD 8.x+, but I do not have an estimate when I can start and how long it may take. In case someone already tested a more recent Fedora version feel free to share your experience.