Simple script to automatically refresh a SharePoint 2010 calendar's items every 10 seconds

RefreshCalendar.html

<script type="text/javascript">
  setInterval(function() {
    try {
      var calendar = SP.UI.ApplicationPages.CalendarInstanceRepository.firstInstance(); // Get the first calendar instance on the page
      if (calendar) {
        calendar.refreshItems(); // async refresh of calendar items
      }
    }
    catch (e) {
      // ignore
    }
  }, 10000); // Every 10 seconds
</script>