I would like to have groups created by admins and used by all.  However, I don't want my users to create new groups.  How can I do that - I don't see any permissions control.

I saw a fairly hairy discussion about whether this system should or shouldn't have some sort of user permissions - how can it not?  If I ever want to change the behavior of the site from the default, am I going to have to hack up php code and hope for the best?

I don't mean to sound snide but I find myself continually saying "I must have missed something here."