Google has launched an upgrade to its mobile maps tool that allows people to track the movements of consenting family and friends, but privacy experts are warning users to make sure they're aware of what it means to sign up.

Google Latitude launched Wednesday in 27 countries, including Canada, and will be available to anyone who has a mobile device that can run Google Maps for mobile. The service allows the user to automatically provide chosen family or friends with their current location.

"We think that the question 'Where are you?' comes up in life quite often and we're hoping this feature will help people answer this question before they even need to ask it," said Google spokeswoman Tamara Micner.

She suggested it might be handy when people are:

• At a noisy, crowded event and want to find their friends without calling them.
• Passing through a neighbourhood and want to see which friends might be available to meet them.
• At an out-of-town conference and want to see whether they know anybody there.

A similar but less powerful tool introduced in 2007 allowed mobile phone users to check their own location on a Google map with the press of a button.

The accuracy of Google Latitude is similar and can range from a few metres to several thousand metres, depending on whether it can use a phone's GPS capabilities or must triangulate based on information broadcast from cell towers or Wi-Fi access points, Micner said.

The service will run on Research In Motion Ltd.'s Blackberry and devices running on Symbian software or Microsoft Corp.'s Windows Mobile. It will also operate on some T-1 Mobile phones running on Google's Android software and eventually will work on Apple Inc.'s iPhone and iTouch.

Privacy settings allow users to hide, lie

Google Latitude's privacy settings allow people to choose the level of detail they want to provide about their location, such as whether they only want to share the name of the city or pinpoint what intersection they're at. Users can also hide their information, turn the service off temporarily or lie about their location by setting it manually.

Only a user's current information is stored by Google, so she won't be able to use the service to track where she or her friends were last week.

"That's where Google Calendar could have come in handy though," Micner said with a laugh.

Google has no plans at the moment to run ads on Google Latitude, but Micner would not say whether it might do so in the future.

"We're always looking to improve our products and expand them in ways that are beneficial to our users," she added.

Valerie Lawton, a spokeswoman for the Office of the Privacy Commissioner of Canada, said the office hasn't yet had a chance to look closely at the new feature.

"But any location-based service will raise privacy issues," Lawton said in an email Wednesday. "We've seen with other Web 2.0 tools that people aren't always aware of the potential implications for their privacy."

She suggested some questions people might want to ask themselves about location-based services like Google Latitude:

• Who do I really want to share this kind of personal information with?
• Are there places I go that I don't want my friends and family to know about?
• Am I going to remember to block my location every time I am somewhere or doing something that I don't want them to know about?
• Is there a danger that people are going to make incorrect assumptions about what I'm up to — say, when I am sitting on a bench that happens to be outside a strip club or a public health clinic?
• Is it possible this information about me will be used for other purposes?

Google Latitude isn't the first service of this kind. Loopt Inc., a three-year-old company near Google's Mountain View headquarters, already has a mapping social networking tool that is compatible with more than 100 types of mobile phones.

With files from the Associated Press