I would think that etiquette would require that you contact the person when posting their messages. Magistrates cases aside, it won't hurt anything to get permission before you make comments public.
As far as making it a rule to not post other's messages, I dunno. Some people do not use the forums so we may lose some juicy gossip that no one cares if it's spread. I guess that isn't much of a loss to protect IC interactions.
