Its an ANSI C library that does allow communication with google calendar and
contacts, useful if you need to support this in a C or C++ application.

Currently, libgcal implements:

 - authentication
 - get all events/contacts
 - atom stream parsing
 - access to individual events/contacts
 - add/delete/edit using gcal objects
 - add/delete/edit using raw XML
 - query for updated events/contacts
 - use of http proxy
 - timezone
 - contact photo download/upload
 - google data protocol GCalendar 2.0 and Contacts 3.0
 - can be used with a C++ application
 - google hosted accounts (i.e. joe@foobar.com)