That's excellent to hear. @Hope33, feel free to disregard what I said previously then
I might have known that if I had gotten a fresh install working lately. I plan on getting one up today so I can launch soon.
Otherwise I think it could be done via the hook filter:topics.addPostData? Just iterate over the posts array, get the category, and for every user of a post add an object to custom_profile_info with the property content set to some HTML indicating moderator rights?
Probably this... alternatively, use the groups method, but hook into filter:topics.addPostData to remove the group badge if they're not in the category that user moderates?