The developers of the iPhone app GasBag, which helps iPhone users find the cheapest gas for their cars, are working on a new mobile friend locator service, Stalqer. This clever and aptly named service has two technologies that are unique, as far as I know, to help it get around two of the big problems found in other friend locators like Foursquare, Loopt, and Google's Latitude.
Problem 1: On the mobile platform that matters, the iPhone, there's no way to do real-time location reporting without running an app all the time, and the iPhone doesn't allow background processes. And even if it did, it would draw down the battery. The Stalqer solution is to create a dummy e-mail account that pings the Stalqer servers whenever the phone polls for mail, which is, by default, every 15 minutes.
When the phone hits the Stalqer e-mail servers, it sends along Internet gateway data, which can be used to locate the phone. It only works when the phone is connected via Wi-Fi, not GSM. It also doesn't get data from the phone's GPS sensor, but it's a clever hack on the way to the creation of more robust location reporting features.
Competing mobile social apps require the app (Foursquare, Loopt) or site (Latitude) to be open for the user's location to be reported. Or they require a phone that supports background processing, like an Android device.
CEO Mick Johnson told me there is another company that has this idea, but nobody has yet released a product based on it.