I am using Racine’s MyNextManagerV2. it was a bit of a pain to set up as I am using Google Authentication rather than nest but the amount of data it surfaces over the API is amazing.
the motion sensor triggers are pulled though via webcore using an"auto_away is ‘true’" piston that updates a virtual Motion Sensor which is then used by Smartthings.
its a really neat setup - motion is detected right away, then Nest changes the auto_away status to false for 600 seconds.
This setup has enabled me to use the nest protects as security devices which is pretty amazing as they are already hard wired into the mains and installed centrally in each room