Twitter For Location or the FireEagle platform has open APIs which can send and receive data. It can stream your location information. This can help third party web services gather vital information about your location even without asking from you.
FireEagle, built entirely on Ruby on Rails, a open source framework is an insight from the search product from Yahoo, ZoneTag. This platform would provide information on where you live, the city name, the zip code and can control peoples information on their location.
FireEagle also provides privacy features where a user can log off tracking of their geo location and can also delete all information stored related to their travel. This would be greatly useful in mobile applications like cell phones and Nokia phones with Symbian s60 might carry one of these.