Mountain View, Calif.
It's a Saturday afternoon; do you know where your friends are? If you and they have Loopt installed on your iPhone, BlackBerry, or any one of about 100 different wireless phones, there's a good chance you can see where they are in relation to yourself, and maybe meet up for lunch. Loopt uses your phone's GPS capabilities to show your location to others you select on a map displayed on the phone. Carriers that support Loopt include Sprint Nextel (S), Boost Mobile, Verizon Wireless, AT&T (T), and T-Mobile (DT).
YouNoodle on Loopt