Notify user when they've been added to a group

Say a group manager adds some subscribers (users) to his group (/og/users/34/add). The user can is now subscribed, but we're leaving it up to the manager to tell the user personally, or for the user to notice a new group has popped up in their My Groups block (which can be confusing). I say, on the form that allows manager to add subscribers, allow for a notification e-mail to be sent.

Ability to send a notification e-mail is already on the regular "invite friend" page, which alerts user that they *can* subscribe. But a manager should have the ability to send a notification e-mail that alerts the user they *are* now subscribed to said group. Should be optional (or maybe it shouldn't, or leave that choice to user 1), default to "send notification".

(Also, might be a good idea to add the [invite friends] tab to the subscribers list, so regular users see that there.)

See attached screenshot for how Google Groups does it.