My wishlist for categories support on Community Server which I recently posted on the official forums. Some of these (global categories especially) I've mentioned in the past...
1. Better category management. As it stands, it is pretty tedious to change categories - you have to enter each post, click a different tab, change the category, save, and repeat. This needs to improve. I'm thinking something along the lines of "painting" a set of posts with a category, or something similar to how Outlook 12 handles categorization of individual posts.
2. Uncategorized Posts. Include an "Uncategorized" group in the categories list. I often forget to categorize something when I post it initially and it's not easy to go back and make sure soemthing has been put somewhere.
3. Global categories. Ultimately, I'd like to have a series of "virtual" blogs here for technology, law, and gadgets. I could certainly just create real blogs for each of these and ask people to post there, but then we lose the individual nature of blogs (i.e., the author pivot). By adding global categories, we could easily roll those up into such virtual blogs.
4. Sub-categories. A lot of the category information is hierarchical. I generally have broad stroke categories like law, technology, personal, etc., but I'd also like to allow users to drill down into something specific. Unfortunately, while I can put something in multiple categories, I have no ability to present meaningful information about the hierarchy involved. Being able to nest them would solve this problem.
I haven't heard any reply as to whether any of these are being considered. Maybe I'll take a look at this next month if I have some time, but it would be awesome if someone else decided to pick it up! (LazyWeb)