It almost works this way now except that an admin needs to configure each gallery.

Now that i re-read your message, I am seeing this doesn't work how you wish at all.  you would have to actually place a module for each user you want to have access as admin to it.

Now, this need you are asking for may show up in our roadmap at a later date but we first need to make what is there already work better.  We also have to convert to the dnn file manager and to an sql dataprovider.  Most use cases only require one user per gallery normally, so because of this and the other mentioned reasons I can't see this being a target prior to 2006.