Vim is well-supported on FreeBSD, thanks to David O'Brien. Unlike Emacs though, there is no infrastructure to facilitate the installation of Vim scripts through ports.
Debian installs scripts into a shared location, but they are not enabled until a user runs an utility to copy needed scripts into his home folder. Per-user script stacks are thus achieved. This is highly desirable since many scripts are quite slow, or simply incompatible to each other. However this package-management-inside-package-management appears quite complicated.
If we focus on personal computing, the per-user functionality may not be needed. Moreover, it might be achieved in the future if support for per-user ports installations is implemented. We should probably try to solve the problem in an easy way, that is, once a script port is installed, it is enabled right away.
On and off, work on bsd.vim-scripts.mk has been under way. http://www.vim.org/scripts/index.php is considered to be the main, almost exclusive source of scripts. One problem is that scripts are present in a variable of formats. Another is that all downloads go through a php script which is not very fetch-friendly.
An alpha-quality vim-script-farmer script has been written to download and repackage scripts in a uniform way: http://heka.cenkes.org/sat/diffs/vim-script-farmer. The infrastructure still lacks the part which would upload the new tarballs into some kind of a repository.
The alpha-version infrastructure with 5 sample ports is available here: http://heka.cenkes.org/sat/diffs/vim-scripts.tbz