Apple iCal
Copy the iCal URL by Control-clicking (or by holding the mouse button for a while, or right-clicking if you have a multi-button mouse) on the green iCal button.
http://www.google.com/calendar/ical/3kcnpi0aif9rthh909gqcjtfls%40group.calendar.google.com/public/basic.ics
Now open iCal, then click Calendar on the menu bar, and then Subscribe.
You can then paste in the URL from department calendar above into the subscription URL text box.
iCal will then create a calendar for you. You can rename the calendar as you please, and you can define the refresh interval. You can even remove the alarms and notifications if you wish.
When your Department Calendar is updated, you can either manually tell iCal to sync the calendar with the online version, or it will automatically download updates according to your defined frequency. Of course, this is one-way syncing only. For now, Google Calendar does not support two-way syncing with iCal, but third-party applications are being developed for this purpose (more on this soon).