This plugin allows you to embed a native looking calendar page on your forum that is linked and controlled by a Google Calendar, without having to resort to using a shoddy looking iframe embed.
Use the Google Calendar interface to create events and mange events, but display them for whoever has the appropriate permissions on your forum.
It could be an admin only calendar, for sharing events with staff, or it could be a public calendar to share events that are wholly controlled by an admin or anyone in the organisation with permissions to control to Google calendar.
Screenshots: