Google have announced that calendar events containing a Google group will now update as members leave and join.
If you have lots of Google Groups in your organisation or domain chances are that you'll have use some of them to set up long term or recurring events. Until now those groups were static in an event - ie the attendees did not update as the group members changed. Now though, Google have announced that the attendee list will automatically update as people join or leave the group. This is great news, tempered only by the fact that it applies to new events set up - but you can edit any existing events by re-inviting the group(s).
For all new events set up - after the roll out - when a user joins a Google Group, they will be added to all of its meetings. And if a user leaves a group, those meetings will be removed from their calendar. Now you don`t have to worry about missing your new team meetings or having your calendar overrun by events that no longer matter.