"Fun aside, we recognize the sensitivity of location data, so we've built fine-grained privacy controls right into the application," Google said in a blog post announcing the service. "You not only control exactly who gets to see your location, but you also decide the location that they see." Friends' whereabouts can be tracked on a Google map, either from a handset or from a personal computer.
Google's new service is similar to the service offered by privately-held Loopt.
Companies including Verizon Wireless, owned by Verizon Communications and Vodafone Group , already offer Loopt's service, which also works on iPhone from Apple .
Latitude will work on Research In Motion's Blackberry and devices running on Symbian S60 devices or Microsoft Corp's Windows Mobile and some T-1 Mobile phones running on Google's Android software.
The software will eventually run on Apple's iPhone and iTouch and many Sony Ericsson devices.
In 2005, Google acquired, but subsequently shut down, a location-finding service that used text messaging to keep mobile phone users aware of their friends' proximity.