So I just tried this, here's the walkthrough:
Log on to your Google calendar. Go to Settings->Calendar settings, click on the tab "Calendars" and click on the calendar you want to view in Calibre. Copy the link for the "Private address" XML feed. Edit to say: This really has to be the private address. In my (admittedly quick) test, the public address didn't work.
Now for the Calibre part (and, since I'm using the german version, I might be a bit off on the nomenclature, but the principle should be clear): In Calibre, add a new individual news source. If it isn't already, switch the window that pops up to basic mode (there should be a button in the upper right half). Paste the private address you copied from Google into the "Feed URL"- field, give it whatever title you like and add the feed (below the input boxes). Give the recipe whatever name you like (below the text, to the right), then, on the left stack of buttons, add the feed. You now should have a new feed in the list to the left with the name you input earlier. Now, all you need to do is set this feed to fetch however often you like (you do this in scheduled news download) and you should be good to go.
This gives you a pretty basic but relatively informative list of events in the calendar. Included are title, date, location and description of the event. For whatever reason, when I tested this, the next event to come went all the way to the bottom, and the last event in the calendar went on the top, but that may have to do with the order I input the events in.
Hope this helps.