Sumatra Development leads the field of migrating entire calendar servers to Exchange. We migrate Oracle Calendar Server, Oracle Beehive, Apple iCalendar, and Zimbra to Microsoft Exchange keeping all meeting information and resource bookings intact. We migrate calendars server-to-server between Exchange and Office 365 while keeping meetings live and doing incremental syncs quicker than any other solution.
We've had some requests from Western Australia lately, so here's the cmdlet working with holidays in OZ.
September 16, 2014 update. Read this post to download the cmdlet. February 23, 2015: Folks, please leave us some feedback about what you like in the cmdlet and what you'd like changed. We see how many of you are downloading it. We'd love some feedback.