I'm still new to moodle but from what I've seen so far this tool is great!
I understand Moodle 1.5 will have category hierarchies something I am really looking forward to. I'm guessing the implementation of this will be such that if you select a category to search on all the questions in the sub categories will be displayed as well. Can you confirm this is the case?
Also as a suggestion perhaps the ability to have mutiple category structures and to allocate a question to a category in each structure would be beneficial.
As an example in NSW, Australia there is a science syllabus for year 7 - 10. I'd really like to be able to store the Science Syllabus structure in a category hierarchy and store another category with generic topics. ie cells to allow increase the ability to search for questions.