Starting tomorrow Google will completely drop support for EAS leaving many Windows Phone users out in the cold. If you haven't received the GDR2 update you won't be able to sync Gcal and Contacts.
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Google has reversed an earlier decision and will now allow all developers to access its CalDAV calendar API, and has also opened support for the CardDAV contact API to the general public as well.
The update for Windows Phone that will support CalDAV and CardDAV will arrive in the first half of 2013 according to a product manager for Windows Phone who was interview by a German media outlet.