In order to subscribe to your own Google Calendar, first log into gCalendar (as I like to call it). You'll notice the Manage calendars link on the left hand side of your calendar (highlighted in the picture to the right).
Go ahead and click on that, and continue reading this tutorial, after the jump. After you click on 'Manage calendar' you should be in the Calendars tab of the Calendar Settings screen. Click on the 'Sharing' setting as highlighted below:
This whisks you to 'Share this calendar' where you can pick to publicly share a calendar (as we have done below) or share it with only certain people. I have decided to share all my information with the world because everyone is always hounding me for appointments (Steve, I'll pencil in lunch with you next time I am in Cupertino, I promise!).
Now just click on the Calendar Details tab, and you'll see a whole bunch of info about the calendar you are currently in. The part we care about is the 'Calendar Address,' which is the web address that iCal needs to subscribe to your calendar. Simply click on the green 'ICAL' button shown below.
Clicking on the ICAL button will result in this pop up (remember this doesn't work yet in Safari);
That's the address we need for our iCal calendar. Copy it, and create a new calendar in iCal. Command click on the newly created calendar and pick 'Subscribe' like so:
Paste the web address you got from clicking on the green ICAL button into the 'Subscribe to' field:
Give it a name (I'm so clever with my names):
Click 'OK', and there you have it! Events you add to your Google Calendar will now show up on this iCal calendar (though you can't actually add events using iCal, which is kind of a bummer).