I think a single "BAN-thread" that only MOD's can edit with the name of Banned person with a link to the post that resulted in a ban (with a quote of what resulted in the ban if post is deleted/edited) along with an short explanation why this resulted in a ban (Ruled to be against policy X would do). This would answer the questions and also help the users understand where the lines are drawn.
Now I understand that modding is alot of work but banning someone is a huge deal for the person getting banned and to some extent online friends of this person who suddently can't communicate with the person so openes about the ban, although more work should be a priority to help keep a good mod-user relationship and defuse any mod abuse thoughst people might have.
