"Google's CalDAV page already lists the API as being "deprecated." A note on the page adds "If you think you have a compelling use case and would like to be whitelisted for the new version of CalDAV API, please fill out this form."

...

Google, however, confirmed this will not impact the agreement with Microsoft and that the Softies will still be able to implement CalDav support on Windows Phone."

http://www.zdnet.com/microsoft-in-the-clear-to-add-google-ca...