buro9: Very nice! We have a message board of 17000 posts/week and we will definitely give this a shot if you can get this to final release. I think it will be popular and a fun thing to build sense of community.
I agree with your thoughts of keeping the information secret from administrators. Besides privacy (which is a good enough reason by itself) think about it this way: how many administrators would want people bombarding them begging for hints or clues?