Ciaran,
we opened bboard-forums for study groups, and each ist studying a different main topic each semester. So categories help me to categorize announcements and subjects better according to different subject matters and groups without having to create too many forums. Too many forums is a disadvantage because at last all study groups have to go through the same subjects sooner or later so it is better to build a common knowledge base and people are too lazy to browse a lot of forums.
So, although our forums are fairly new and we don't have much experience, I think we will make extended use of the categories. Since we use the forums for announcements and also sharing study materials to the students, many of the postings are done by ourselves, so we have it in our hands to use categories.
Also, we are using Postgres instead of Oracle, so "Oracle text themes" may not be available.
