So it looks like DragonFly has been making considerably progress since the last time I looked in on them.
Most significant (in my opinion anyway) is the fact that they've implemented variant symlinks.
They're symlinks with variables in them, which are replaced with the contents of variables that can be set on a per-process, per-user, or per-system basis. All you VMS people out there are probably thinking "wow, that's a lot like logicals", and yeah, it sure seems like it.
Interesting places to look in the code if you're curious would be the command line tool for messing with the variables, and kern_varsym.c where much of the magic is implemented.
Neat stuff all around. I'm looking forward to giving DragonFly a try at some point.