About users

I don’t know if this feature is just developed for a new version of WP but I need to have a new kind of user or an expansion of Author user.

I mean that I have to give to author users the possibility to create a new category in one of that I’ve already created and inside that category, linked to his name, he can create how many subcategory he wants to write many blog or chapter of just on blog in the same subcategory.

Anyway he can’t modify the administrator’s categories and sub-categories nor sub categories of other Author users, but just the own.

Is it possible to implement it right now with some plug in or is a possible future feature?

Thank you.