I was invited by the Ark Group to present at their Web 2.0 for Business seminar on how the State Library was using Web 2.0 applications. The presentation before mine was from the Office of Crime Prevention, which is part of the WA Police Department on their use of Facebook for School Leavers week. They have been using Facebook since 2005 to promote their stay safe and look after your mates messages as well their events. All very low key and well target, that is why most people over 21 knew nothing about them but from all accounts very effective.
Unfortunately, the school leavers site is undergoing major revision and the facebook presence for 2009 has not been launched. So like me you will have to check back in September or October.