I could go either way on this, but Elias does have a good point.
Allowing a tree hierarchy does make things more complex in the UI code and for the user. Look that the ugly category and bookmark management UIs (you really need a tree control to do them right). And I'm not even gonna mention the code that supports HierarchicalPersistentObject. I think hierarchies are important to expert users, but other users generally don't use them. Look at interfaces like iPhoto or iTunes or GMail, they all have flat hierarchy of collections -- 2 levels like Elias is suggesting. What I'd like to see in the file-uploads area is metadata, we should be able to save title, summary, category and tags for each uploaded file. If you want a hierarchy, view by category. If you want collections, view by tag. - Dave
