Google Latitude is mobile social map app that shows you where your friends and family are. 
Latitude is a new feature for Google Maps on mobile devices. It can also be used as an iGoogle gadget on computers.
Once a users opted in to Latitude, users can see the approximate location of friends and loved ones who have decided to share their location with the user.
Latitude users can do things like see if a spouse is stuck in traffic on the way home from work, notice that a buddy is in town for the weekend, or see if somone's flight landed safely, despite bad weather.
With Latitude, not only can users see your friends' locations on a map, but they can also be in touch directly via SMS, Google Talk, Gmail, or by updating your status message. Users can even upload a new profile photo on the fly. The Google Mobile bog notes "It's a fun way to feel close to the people you care about.."
Google recognizes the sensitivity of location data, so they built fine-grained privacy controls right into the application. Everything about Latitude is opt-in. User control exactly who gets to see their locations,and decide the location that they see.
Latitude allows users to change the settings on a friend-by-friend basis., Latitude is available in 27 countries, and we hope to add more soon.
From a mobile smartphone, visit google.com/latitude on the hone's web browser to download the latest version of Google Maps for mobile with Latitude. Latitude is available on Blackberry, S60, and Windows Mobile, and will be available on Android in the next few days. Google expects it will be coming to the iPhone, through Google Mobile App, very soon.