Scheduled Release: Calendar events that update when Google Groups change
Starting today when Google Calendar invitations are sent to members of a Google Group, the attendee list will automatically update as people join or leave the group. When you join a Google Group, you will be added to all of its meetings. And if you leave a group, those meetings will be removed from your calendar. Note that groups stop dynamically changing when the total number of guests in the event crosses 200.
Release track:
Scheduled Release
Editions included:
Google Apps for Business, Education, and Government
For more information:
http://googleenterprise.blogspot.com/2013/11/calendar-events-that-update-when-google.html
https://support.google.com/a/answer/172013
Reference by : http://www.google.com/