I've done several things:

  .LRN Site Wide Administration
      -  Administrators UI
      -  Edit community parameters

  I created a new group, dotlrn-admin, this group has permissions on
  dotlrn only. Users in this group can create users, classes,
  communities, etc...
  dotlrn-admin users does not have Site Wide permissions.


  - Users
    I removed  site-wide admin toggle

  - Edit community parameters
    There are new parameters for group administration. (classes, communities)


  Try it here:  http://smeagol.galileo.edu:8090
  Site Wide user:    test@oacsadmin.com    pass:  test
  dotlrn-admin user:  test@dotlrnadmin.com  pass:  test
  professor:          test@professor.com    pass:  test

  Please test it, create users, classes, etc ...
  Please post any comment, bug, suggestion in this thread or email.