As you’ve probably seen from using the site, there’s two ways that a user can log their location, they can log that they are at one of their favourite locations, by using a favourite “label” or they can log that they’re at an arbitrary location using a specific latitude and longitude. The API method for updating the user’s location allows for either. It also allows you to specify the time that the location was recorded, this allows you to store up updates and submit them at a later time. Requests to update a user’s location can be done with either a GET or a POST, here’s a few examples to get you going:
http://mapme.at/api/mapme.json?lat=53.404284475&lon=-3.03645293
http://mapme.at/api/mapme.json?label=home
http://mapme.at/api/mapme.json?lat=53.392338&lon=-2.593460&time_logged=Mon%20Feb%2016%202009%2018%3A22%3A20%20GMT%2B0000%20(BST)