If you use Address Book’s near-hidden feature of including a birth date in someone’s record (in Address Book’s menu bar, select Card > Add Field > Birthday), you can now get those birthdays to automatically show up in iCal. All you need to do is:

  • Open iCal (located in your Dock or in your Applications folder)
  • Open iCal’s preferences (iCal > Preferences, or Command-,)
  • Turn on “Show Birthdays calendar”

A new calendar called Birthdays appears in iCal’s list of calendars to the left. (Notice the little birthday cake icon to the right of the calendar name.)