Google Map Public Calendars

Google Maps Public Calendars


example
http://www.google.com/calendar/events?q=Marathon
&ql=London&qt=&qtd=&sa=N&page=vl&afp=393d85a865eecf88

A New Feature in Google Calender is to be able to search Public Calenders and Events

"Now you can search the web for events and add them directly to your Google Calendar. Within Google Calendar, type an event search into the search box like "Symphony in San Francisco" and click "Search Public Events". You'll see a list of events that you can easily add to your Google Calendar."

more new features
http://www.google.com/intl/en/googlecalendar/new.html

There is also a Google Calendar API

The Maps for calendar only work when the user has inputted the location of the event.
All Events should have a location, therefore should be mapped.

Source:Mapperz

Though please remember Google Calendar is still Beta.