Wired on Friday Ever had the feeling you were being followed? You may as well get used to it. These days we are rarely out of contact with the office or loved-ones, whether it be via email or, more especially, the mobile phone.

But soon we will find ourselves tracked and pinpointed whether we like it or not - even though most of us will find this useful.

It's not as futuristic as it sounds. Mobile phone technology is already capable of working out where you are using old-fashioned Pythagorean mathematics. It's a process known as triangulation. Take three mobile phone base stations, measure the strength of your mobile's signal in relation to the base stations and, hey presto, your location can be determined to within 300-500 meters.

As new third-generation (3G) systems arrive, these will be able to track your location to less than a few metres. Even more accurate phones are about to be introduced in Japan, which contain chips using the satellite-based global positioning system to determine the phone's location down to a square metre. Not only does this capability mean we will have to think seriously about the privacy implications (as Karlin Lillington has been tracking in a number of recent stories), but, on the other side of the coin, there are potential benefits.

Last week, the makers of London's black taxis began an automated service that finds a mobile caller, the nearest taxi to them and then calls the driver. For this you pay £1.60 sterling (€2.30) on top of the metered fare. Of the 12,000 black cabs roaming London daily, 500 are equipped to respond, according to Zingo, the subsidiary of Manganese Bronze, which provides the service.

More than 6,300 people have tried it since the beginning of the company's trial this year.

The trend to introduce location-based services caught on long ago in Japan and already other services are coming on-stream.

Last week, the Hong Kong mobile phone firm Sunday Communications started "Loved-Ones Radar", allowing parents to track, to within 500 ft, the location of their child's mobile phone - not that this is particularly popular among the teenagers it hunts down.

Despite this flurry of recent launches, these services have been a been a long time coming. So-called "location-based services" were among the great white hopes of the hype-filled mobile phone industry three years ago, but it is only now that we are seeing a handful of services appearing. Then, there was much talk about a service that would offer two friends within a mile of each other a discount if they met in Starbucks. That project failed, in part because the profit on a Starbucks cappuccino is just too small to offer the discount.

Other early "mobile coupon" trials produced mixed results. ZagMe, a project at the huge Lakeside and Bluewater shopping centres outside London started in June 2000, targeting shoppers with "ZagPoint" SMS coupons on specified purchases as they walked around. But it ended up appealing to about 10 per cent of users and the profits on small purchase coupons were minimal.

In the end, ZagMe failed to attract further investment, even though the technology worked. So the mobile industry went in search of different kinds of services based on location. These days the services are more modest but have more practical applications.

Analyst Forrester Research has noted that the location-based applications that work best are simple, quick bites of time-sensitive information. Therefore, mobile services that find the nearest taxi, mechanic, ATM, restaurant or - predictably - toilet, have proved by far the most successful to date.

Others have sprung up. Stockholm's TeliaSonera offers Friend Finder, which alerts subscribers to when their friends are nearby.

In France, it's location-based chat and flirting that has pushed the buttons of subscribers to the France Telecom service.

But, as Forrester points out, data services in general remain only a small percentage of the operator's business - between 10-14 percent.

Location based services, where they exist, are but a tiny fraction of that. As usual, most people find it easier to text the person they are after. And sure enough, 98 per cent of data services are person-to-person text messages.

But the trend towards these services is as inexorable as our love for our mobiles. In the westernised world, we are slowly but surely becoming inextricably tied into a mobile existence, which mirrors our real-world location and activity.

A recent report from the Henley Management Centre and Teleconomy, found that 46 per cent of 25- to 34-year-olds could not live without their mobile. According to an In-Stat/MDR study in Japan, 68 per cent of consumers planned to buy a location-enabled handset within the next 12 months.

And it is the sociological aspects of what happens when mobiles and a host of other devices become "aware" of their location that are perhaps among the most intriguing to contemplate. Almost like animals leaving their scent trails, our mobile devices will make us invisibly aware to those people and objects we choose to locate around us, and which choose to locate us.

Shortly, it will be possible to find love, literally, as you walk into the bar.

As the Headmap.com - a website that looks at the social implications of these new services - puts it, you will be able to "search for sadness in New York", you will find notes in boxes that are empty, and "in a strange town, you knock on the door of someone you don't know and they give you sandwiches".