This is close. I actually hacked 115 to do it but never had all the issues taken care of.
I'm not necessarily looking for people to leave comments about the person. I think of it more as people leaving questions/polls in their profile for other users to respond to. For example, if you go to
http://bolt.com, they have a feature called the tagbook that does just this (tyr clicking on a username and then click tagbook). I think the more you can enhance the user profile, the more sticky your site is. It truly develops community and users' personality within that community.
Will wluke's hack allow users to edit/moderate their own guestbook?
I don't want a feature that causes tension between my users, but rather creates dialog amongst them.