It is a nightmare scenario for snoozing delivery men, love rats and all teenagers: technology that can track a person’s location virtually anywhere in the world, 24 hours a day. At the moment it’s only voluntary and it’s called Google Latitude — part of the company’s free Maps for mobile navigation software. Once installed, it will identify anyone from your mobile’s contacts list who is also running Latitude, with the option of sending them a request to share their location. If they agree, you’ll be able to see where they are whenever their phone is turned on.

Their location is pinpointed on your phone screen as a symbol overlaid on a Google map. The person has the option of adding a commentary on what they are doing, or an invitation to others to join them, such as “Coffee, anyone?”

Millions of phones already have an earlier version of Maps for mobiles, which works on smartphones and more humble handsets alike, allowing users to see their own location. The upgraded version — which is available now for BlackBerry, Nokia or Windows Mobile phones — is the first that allows them to view the location of others.

Google suggests uses for Latitude such as “Only head to a party when you see that several of your friends have arrived” and “See who is in town before planning your Friday night”.

All fine, but what about more potentially intrusive uses?

Google — a company that was founded on the principle of “Don’t be evil” — has been heavily criticised over its policy of holding the details of users’ internet searches, and was forced to pixelate the faces of anyone captured in its ongoing mission to photograph every inch of Britain’s high streets. So it is touchy about the privacy issues involved in its latest project. “It just lets people do what they’re doing already, but more easily,” said Mat Balez, product manager for Maps for mobile. “It helps if you’re arranging to meet up, or co-ordinating activities.”

There are some privacy safeguards: when you first agree to share your location you can blur its accuracy to simply show which city you are in, and modify that accuracy for each contact at any time. You can also hide your location altogether. Then there’s what Google describes as a “fun feature”: the ability to instruct Latitude to broadcast a false location for you.

Latitude is undeniably accurate. If your mobile is equipped with a global positioning satellite transceiver, the service can pin down your location to within a few square yards. If you don’t have a GPS facility on your phone, or the satellite signal is blocked, Google triangulates your position by working out your distance from the nearest mobile phone masts — not as accurately, but to within a claimed typical building length in a city. There are plans to roll out the technology to laptops and home computers, which would allow users to track mobile phones from their homes.

Latitude is another move by Google to put its software at the heart of our lives. The messaging and photo upload features are strikingly similar to the sort of feeds so popular with users of Facebook, Twitter and other social networking services.

Rival trackers

Brightkite

Describes itself as a “mobile friend finder”. Like Latitude, it enables you to upload pictures and messages and state your location, which you can also share on the company’s website or via Facebook and other social networking sites. brightkite.com

Fire Eagle

This Yahoo service doesn’t update your details automatically, leaving you to enter your location as you go. But its ability to share pictures and extra information is similar to the Latitude service. www.fireagle.yahoo.net

Num8

Aimed at fretful parents, this British-designed £149 wristwatch-like device, right, contains a GPS chip that broadcasts a child’s location to within a few yards. The watch cannot be removed without alerting you. A £4.99 monthly subscription enables you to track its location over the web. www.lok8u.com

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