This calendar can be seen with many popular applications, overlapping on your own calendar, and updated in real time.
Some of those applications are: Google Calendar, Apple iCal, Lotus Notes, Novell Evolution or GroupWise, Mozilla Sunbird or
Thunderbird with Lightning extension, Windows Calendar, etc.
For a more complete list, see: http://en.wikipedia.org/wiki/ICalendar

GMail users:
Select the "Calendar" link above the GMail logo, or login at calendar.google.com
Click on "Manage Calendar" on the left, under "My Calendars"
Click on "Add by URL" next to the "Search Public Calendars" button,
Click on "Friend's Calendar",
Type: calendar@yavnehdayschool.org
Click on "Add"
Go back to your calendar, and you'll see "Yavneh - Public" listed.