"Google Calendar allows Web application developers to access
user-generated content and event information through its REST-based
Developer API. PHP's SimpleXML extension and Zend's GData Library
are ideal for processing the XML feeds generated by this API and
using them to build customized PHP applications. This article
introduces the Google Calendar Data API, demonstrates how you can
use it to browse user-generated calendars; add and update calendar
events; and perform keyword searches..."
