Essentially, three things:
1. A designated maintainer who'd be willing to commit to resolving
FreeBSD-specific issues, if any. The core team is pretty swamped right now,
so this needs to be someone new.
2. Information on the de facto standards for user-friendly packages,
installs, and uninstalls on FreeBSD systems -- preferably in the form of
patches. (Effectively enough to make sure that the FreeBSD version is as
easily installed as the other platforms. This is likely to eventually
include porting our graphical setup program to GTK, although that's unlikely
to have any FreeBSD-specific ramifications.)
3. A preconfigured machine to add to our build farm. :-)
AFAIK, the existing sources and makefiles build and run without any trouble,
so the main obstacle is #3.