Just got this off Gizmodo @ Google Latitude: Friend Finding Maps on Smartphones and PCs
Homepage - Google Latitude
With Google Latitude, you can:
Enjoy Google Latitude on your phone, PC, or both.
- See where your friends are and what they are up to
- Quickly contact them with SMS, IM, or a phone call
- Maintain complete control over your privacy
Overview
Share locations
Location sharing starts only when both you and a friend agree. Invite friends via email or easily add them from your Gmail contacts.
Control privacy
You can share, set, or hide your location - or turn off Google Latitude - from the privacy menu. You can also hide your location or share only a city-level location with certain friends. For more information, see the Privacy FAQs.
Share status
Create a status message and upload your photo within Latitude. It also syncs directly with Google Talk. Check your friends' status messages to see what your friends are up to.
Contact your friends
Quickly contact your friends with an SMS, IM, or phone call. You can also get directions to lead you to your friends
Homepage - Google Latitude