Role notifications

Thanks for the great module! Very nice interface..

It would be great to have Role based notifications, i.e. functionality to have users provide the name of a role (or a list of roles) and have all users who belong to that role get subscribed. It would be help and ease tremendously notifying a group of users without having to install/configure/populate organic groups just for the simple purpose of sending out targeted emails.

As a realistic example, we have a computer cluster support site where user roles and accounts get synchronized with an LDAP server (user's group information in LDAP becomes their role(s) in Drupal). It would be a lot harder to do similar thing for organic groups, and even harder to justify the effort where the sole purpose is sending out email notifications.

Thank you very much!