What is by Google's own admission a "glaringly obvious" missing feature has been added to Google Wave. Now, it's possible for participants to be removed (or remove themselves) from waves, potentially saving people all sorts of time or embarrassment. Add someone to a wave by accident? Find out a friend can't attend the event you're trying to discuss? This update addresses the fact that you still would have wound up bothering these folks with all sorts of irrelevant messages.