It's all fun and games until one of your appointmets is specified in rfc2550 format, and the meeting room is on a big ship crossing the international date line on the same day daylight savings time changes for the ship's country while a new timezone is voted into effect. Meanwhile the other meeting room is a videoconfrerence between the international space station and a ship travelling at close to the speed of light, but the real twist is the two meetings don't actually have anyone in common!