Occasionally some things hang on shutdown. Seems to be random as far as I can tell, I'm not always there to watch the reboot.

So far these have hung:
bind9
portmap
deconfiguring network interfaces

It's not always the same ones, sometimes it's none at all, sometimes it's more than one.

No idea what's going on.

I tried throwing "echo dmesg > /var/log/shutdown.txt" into a script in rc0 just before the umount local file systems one, but it hasn't produced a log.

Any other way of getting details like in dmesg on boot for shutdown?

If your system is shutting down correctly that information should be in the normal logs unless it shutdown syslog first.