Know Where Your Friends Are With Google Latitude
Depending on the device you are using, Google's location feature determines your approximate location using either GPS or Wi-Fi. At present, Google Latitude works on the Blackberry, S60 devices, and Windows Mobile devices. Google claims that it will be available for Android "in the next few days;" "will be coming to the iPhone [and iPod touch], through Google Mobile App, very soon;" and will also be available on "many Sony Ericsson devices." Google Latitude also works on any desktop or laptop that is capable of running iGoogle's Gadgets or running Google Gears (which is installed by default when you install the Google Chrome browser). Google Latitude is presently available "in 27 countries and 42 languages," so you can see where your friends and family are, even when they are traveling abroad.
Once you enable Google Latitude on your device, you then send out invitations to others who you want to share your location with--the invitations can go out to anyone with an e-mail address. If that person accepts the invitation, you will then be able to see their location on Google Maps.
As to those who you have allowed to see your location, exactly what information they see is entirely up to you. You can allow Google Latitude to automatically detect your location down to the street or city level (if you are using Google Latitude on a desktop or laptop, you will need to install the Google Gears plug-in to enable this feature); you can set your location manually; or you can even hide your location. You can even control these settings on a person-by-person basis, so different people will see different information about your location. You can add an image that will serve as the icon that represents your location, and you can also add a "status" that will display along with your icon, such as "anyone up for grabbing a drink?" You can also communicate with those you share your location with by sending an SMS message, using Google Talk, or sending a GMail message, directly from Google Latitude. You can also change any of these settings at any time. (One note of interest: We tried Google Latitude on Firefox running on an iMac, and while Google Latitude appears to work as expected, we ran into one glitch: Whenever we attempted to let Google Latitude automatically detect our location, we received the error, "Oops we couldn't process your request, please try again later.")
In terms of privacy issues, Google claims that "Google Latitude only reports your last updated location and does not keep a history of previously reported locations;” and "Google does not share an individual person's location with third parties without explicit permission." This, however, implies that Google has the ability, if it chooses to, to keep a history of previous locations, and provide this information to law-enforcement officials if legally required to do so.
UPDATE: As to that "glitch" we ran into, chalk it up to human error. We forgot to, er, turn on Wi-Fi on the iMac we were using (we typically use the system with an Ethernet connection). Once we enabled Wi-Fi, Google Latitude quickly, easily, and accuratley found our location.