Today the folks in charge of the software universe at Google have let it be known that they're adding CardDAV to the list of open protocols for accessing data on mobile apps and devices. This means that your iPhone 5 is now able to sync with your Google contacts list the same way you're able to sync with Google Calendar and Gmail. Third parties galore - and not just on iOS - will be able to build their own Google contacts wielding apps in the very near future!
One of the most significant changes this will make is allowing Apple to integrate Google contacts into your iOS contacts app. This will not happen automatically, but adding your contacts to your iOS device is quite simple. Google has presented a set of instructions which we've reproduced here - follow at will!
1. Open the Settings application on your device.
2. Select Mail, Contacts, Calendars.
3. Select Add Account...
4. Select Other
5. Select Add CardDAV Account
6. Fill out your account information in the following fields:
Server: Enter "google.com"
User Name: Enter your full Google Account or Google Apps email address.
Password: Your Google Account or Google Apps password. (If you’ve enabled 2 Step verification, you’ll need to generate and enter an application specific password.)
Description: Enter a description of the account (e.g. Personal Contacts).
7. Select Next at the top of your screen.
8. Make sure that the "Contacts" option is turned to ON.
This update also works for Android, meaning that on both systems you'll have IMAP for email, CalDAV for calendar, and CardDAV for contacts. Each will be free and open to software developers that want people to work with this data with their apps and for manufacturers of devices that create their own software builds - like Apple.