I was looking for a way to backup all of my Google Calendar data, and it turns out to be trivially easy. First, login to Google Calendar. Then, simply visit this URL:
https://www.google.com/calendar/exporticalzip
Google Calendar will then pop up asking you to save a .zip file that contains Ical files with every event on every calendar you are the owner of.
Now *that* is awesome. I wish I’d known that a long time ago. Nowadays I use BusySync to sync my iCal appointments to gCal instead.