It may be helpful for organizers to understand the pros/cons of using different calendar services (Facebook, Eventbrite, meetup.com, Google Calendar, BYO CMS that supports iCalendar feed, etc) to publish their events.
Recently, Facebook closed off API access to public page events, and I think we'll see meetup.com do something similar. Might also helpful to touch on what priority gemstate.io puts on different services, and what pros & cons are of each.