The last time Darwin was synced with FreeBSD was FreeBSD 5, at which point the features available in FreeBSD 5 were also made available in Darwin, such as kqueue and various other API's.
I, and some other developers I know, have been hoping that Apple in the future will sync with FreeBSD again in the future, hopefully against FreeBSD 10 to get even more feature parity in kernel interfaces available.
There is a lot of a relationship between Darwin and the FreeBSD team. Apple's firewall import from OpenBSD (pf) for example was also used by the FreeBSD team to update their port.
Just because it is not visible on the surface doesn't mean the relationship doesn't exist ...
I, and some other developers I know, have been hoping that Apple in the future will sync with FreeBSD again in the future, hopefully against FreeBSD 10 to get even more feature parity in kernel interfaces available.
There is a lot of a relationship between Darwin and the FreeBSD team. Apple's firewall import from OpenBSD (pf) for example was also used by the FreeBSD team to update their port.
Just because it is not visible on the surface doesn't mean the relationship doesn't exist ...