That are really excellent news: Yesterday, June 6, 2013, Google announced that it will open Google’s CalDAV and CardDAV APIs for everyone. In contrast to Google’s prior announcement of March 13, 2013, this means that in the near future third party apps are able to communicate with Google calendar via CalDAV and with Google contacts via CardDAV. Syncing contacts and calendars via third party apps will then be possible. Both APIs will be integrated in Google APIs Console and getting OAuth 2.0 authentication.
Stay tuned! 😉