Drupal services add location
Should anyone else have this problem, the correct answer is:

{
    "node": {
        "field_restaurant_location": {
            "und": [
                {
                    "country": "us",
                    "latitude": "-26.2041",
                    "locpick": {
                        "user_latitude": "-26.2041",
                        "user_longitude": "28.0473"
                    },
                    "longitude": "28.0473"
                }
            ]
        },
        "title": "Restaurant from JSON API",
        "type": "restaurant"
    }
}