I have the same question. Is it possible meanwhile?
I could use smart folders. But I'd have to rebuild the whole category structure in a smart folder template. And it wouldn't follow any changes in the category tree.
Similar problem is, when I want to make a folder structure of all document types, all users, or any other property: I always have to hardcode it in a smart folder template, and it doesn't follow when my available set of attributes changes (i.e. a new user).
