As ssl is now mandatory, after some lab work I managed to mitm an Ipod Touch.
It uses as addressbook/database :
https://google.com/carddav/v1/principals/[username]%40gmail.com/lists/default/
where [username] is the gmail user.

In case of future user-agent filtering, ios uses:
iOS/6.1 (10B144) dataaccessd/1.0


2013/5/8 Patrick Ohly <patrick.ohly@intel.com>
On Wed, 2013-05-08 at 02:35 -0300, Juan Antonio Zuloaga Mellino wrote:
> Google carddav stopped working, but there was no announcement.
> The only reference I could find was this thread:
>
> https://inverse.ca/sogo/lists/arc/users/2013-04/msg00008.html
>
> I used to connect with this configuration:
> --CODE--
> syncevolution --keyring=no --configure \
>               username=<user>@gmail.com \
>               password=<password> \
>               addressbook/backend=carddav \
>               addressbook/database=https://google.com/m8/carddav/principals/__uids__/default/lists/default/
> \
>               target-config@webdav \
>               addressbook
> --/CODE--
>
> It fails with:
>
> --OUTPUT--
> [INFO] addressbook: backend failed: error code from SyncEvolution object
> not found (remote, status 404): PROPFIND: Neon error code 1: 404 Not
> Found
> [ERROR] error code from SyncEvolution object not found (remote, status
> 404): PROPFIND: Neon error code 1: 404 Not Found
> --/OUTPUT--
>
> Lack of complains indicates that iPod/Pad/Phone and windows[78] phone
> sync still works.
>
> So it might be true that google started whitelisting the server.
>
> Can anyone confirm this?

I need to check this when I have more time.

> Is anybody working on a google-api for syncevolution?

There's some preliminary code for a google-api to vcard converter in the
gdatasource branch. But work on that stopped before it was usable as a
backend in SyncEvolution.

--
Best Regards, Patrick Ohly

The content of this message is my personal opinion only and although
I am an employee of Intel, the statements I make here in no way
represent Intel's position on the issue, nor am I authorized to speak
on behalf of Intel on this matter.