Google Calendar CalDAV support – Calendar Help Center:
Google Calendar/iCalSo the hunt for a Google Calendar/iCal sync tool is over.  There were tons of third party tools out there, and the free ones I found were either crappy, manual, outdated or some combination of those three.
Luckily for us, Google’s finally made their information accessible via the CalDAV format.  Deedas & I were just talking about this yesterday, and he was a bit pissed that there wasn’t an easier way to do this, but it seems waiting one day is the answer.  In this case. 

Click the link above to read the directions on how to do it.  I’ve tried it, and it works great :)