I would like to have ability to specify access in groups per folder like:

/public uploads/ - every one can upload files
/moderator uploads/ - only mods and admins can upload
/admin uploads/ only admin can upload

also would be nice to allow to few custom users to upload files to some specific folder without adding them to custom user group.

It would be good to have possibility to manage more than 3 user groups, and set custom access for each of them.