Useful, and not only for global 'start of event' notifications.
I often lose track of where the EM is in a hectic event, or catch a glimpse of their text from somewhere saying 'Everyone head South' but I don't know how far! Last night was fairly typical, lateish on in the fight I 'lost' where the battle was and ended recalling back to the EM office and waiting to see if someone came by who could tell me if 'we' won or not. During the event, even a sub-server chat power would help a lot, if they get chance to describe where they are. Before and after, to gather people and announce the outcomes, global chat would be extremely handy.
Maybe a way for them to appear as a unique 'dot' on the radar map (preferably without having to get on the same screen as them to set it up, they tend to be moving about a lot once things get started!) would be useful too.