What Is Google Latitude?

Google Latitude is a new Google service for finding friends on a map, supported on the following types of mobile devices:

• Android devices, such as the T-Mobile G1 (coming soon);
• iPhone and iPod touch devices (coming soon);
• most BlackBerry devices with a color screen;
• most devices running Windows Mobile 5.0;
• most devices running Symbian OS (Nokia smartphones);
• Java-enabled (J2ME) mobile phones, such as Sony Ericsson phones (coming soon).

Read more http://www.google.ru/latitude/intro.html