The Musea team is working on the bboard port this week. The bboard package has 3 more connect by queries on the acs_messages table that need to be ported, plus the one that Jon left in acs_messaging.
I will follow Dan's example and add a tree_sortkey column to acs_messages in order to get these four queries to work in postgresql. Dan's already done this for both acs_objects and acs_object_types, so I expect it will work flawlessly.