Google Mobile Maps has a new feature since today called Google Latitude. It will allow you to broadcast your location to select friends and family based on the coordinates of your cell phone. Also, you can see where they are.
You can keep track of where everyone is at any given time, and from within the app you can call, email, or IM them. Everyone you have opted to follow shows up as a picture icon on a map or in a list view.
Don't worry about your privacy because everything about Latitude is opt-in. You can control who sees your location, and choose which locations are visible (you can even lie about your location, manually setting it to something else). All of this can be set up for each individual Latitude friend.
When you aren't on the go, use Latitude from your computer to see your friends on a full-screen map and get in touch with them. You can share your location manually or use your computer's WiFi location.
Latitude works out of the gate in 27 countries on Blackberries, Windows Mobile, and Nokia S60s. Android will begin rolling out over the next week, and an iPhone app is coming soon. In the U.S., there is also an iGoogle gadget that shows everyone’s location and messages.