Privacy is a key concern with any kind of location-based social networking service, and Google says Latitude is completely opt-in: Users choose who gets access and what level of information they can see. For example, users could grant close friends and family access to their exact location, while limiting acquaintances to knowing only the city they’re in. And for those moments when you need to go into total stealth mode, the application allows you to manually set your location or cloak it entirely.