Oh cool! I guess I just jumped the gun a bit. When I checked earlier, it was still at 3.1 with no mention of "mac68k" in the directory for NBSD 4.
I'll have to download it soon and get it on my Quadra 650.
EDIT: I just realized that the ISO image of NBSD 4.0 isn't up yet for "mac68k", but as you said the 4.0 release files are there. I'm guessing there's some way to update from 3.1 to 4.0? (Sorry for my lack of knowledge with NBSD. :I )