Thanks for the research! It looks like these API's are Javascript based, its actually pretty easy to read GeoLocation with Javascript without a 3rd party API. MM already can read your current location via this, try the target button in the upper right of the map page. I've actually experimented with doing all the tracking with pure HTML5 / Javascript and it works just like the old Instamapper. Problem is: as soon as the phone goes to sleep so does all JavaScript (this is by design of JS for security reasons). The advantage Instamapper had was it was an app that kept running in the background, feeding all the points to the Web and and MM server would keep reading them. As long as anyone was willing to keep their phone from sleeping MM could track you without an app, but that would kill the phones battery.
There are several MM "apps" out there that take the place of Instamapper and talk directly to MM via its API.
