To a large extent this is also the Debian model, which is a lot more integrated than many Linux distributions--- they don't just cobble together a bunch of packages and call it a day. Like FreeBSD, they do take a lot of things from upstream (e.g. both use X.Org as their X11 server), but also like FreeBSD, they heavily customize the core packages and develop them so they work together well. There are core Debian teams working on its versions of the Linux kernel (http://wiki.debian.org/DebianKernel), X.org (http://wiki.debian.org/XStrikeForce), Exim MTA (http://wiki.debian.org/PkgExim4), package manager (http://wiki.debian.org/Apt), etc., along with thousands of Debian-specific patches to other packages, which are maintained as far as possible in an integrated manner to meet the unified Debian system policies.
It's not entirely identical, but I don't think it's that far off. I think the FreeBSD core system may be developed somewhat more as a single entity (for example, because FreeBSD literally develops its own kernel, rather than customizing an upstream one), but Debian may actually have more cohesive development across the entire system. My impression, though I could be wrong, is that FreeBSD ports are more spotty when it comes to really being managed seamlessly with the base system.