Within Google Apps for Business, Education, and Government, Google Groups delivers much more than secure, managed distribution lists. Groups can be used for threaded discussions, shared inboxes, and work flow collaboration. Groups also provide an easy mechanism for sharing documents stored in Drive.
Now, Groups makes scheduling Calendar events easier. When inviting a group to a meeting, the attendee list updates automatically as people join and leave the group.
When joining a Google Group, people are automatically added to existing meetings; when leaving a group, people are automatically removed.
While this change only applies to calendar events created after the feature rolls out, you can adjust previously scheduled meetings by re-inviting the group. Automatic attendee changes works for events with up to 200 attendees.