Calendar sync gives you the opportunity to sync your calendar with your switchboard, both with one time- and reoccurring events.
You can set simple commands like m: to sync that you're in a meeting. You can also add commands that you think suits your needs.
Exchange-servrers that's gonna use the service needs Exchange 2007, 2010 and Office 365. You'll also need a public EWS-adress that's set on basic authentication.
The service needs a user who everyone shares thinner calendar with to work.