Indeed and this set could be consolidated around an ownCloud API. I would even go further make them isolated from google's API by default with options to enable

Indeed and this set could be consolidated around an ownCloud API. I would even go further make them isolated from google's API by default with options to enable tight integration with the platform, if you wish. That is for instance, an address book that does not share your contacts and a calendar app that might share it's event if you explicitly say so, an A-GPS that doesn't report automatically your position to Google ...