[eluser]Jelmer[/eluser]
The question then is: what more do you need?
But most of the answer to that is probably going to have a lot to do with implementation. I wrote a class wrapping those functions for an application of mine which does some input checking and limits where they may be used. But that's very application specific code that can't be ported to another application easily. I'd recommend doing something like that if you're writing an application where users get to create/edit&delete; directories. But CI doesn't come with a basic implementation for such a goal.
Also, when asking such a question and knowing PHP can do it - you might want to include some more specifics in your question or you're never gonna get the answer you're looking for and just the basic answer.