This week saw the launch of a new service from Google that allows you to track your friends via Google Maps either on your mobile or PC.

Google Latitude at first seems like fun: it's a great idea. You're in the pub, you see your mate walking down a nearby street (on your phone) and so you give him a ring to come and join you. Or maybe you are lost and need to get directions to find someone. It will also be really useful at festivals.

So in the good spirit of things I allowed Chris Hall our reviews editor here at Pocket-lint to follow my movements after being alerted to a request from him. New and exciting, on the train into town from Ascot to London, Chris was sending me updates as to where I was.

"You're just passing Egham", I got on IM, and low and behold I was leaving Egham station. Further updates from Richmond and Clapham Junction proved the service worked. All good clean fun.

When I eventually got to Waterloo, I stopped for a coffee with a friend (not on Google Latitude) then jumped on the Tube and forgot about Google Latitude and the fact that Chris was tracking me.

Thirty seconds after popping out at Chancery Lane Tube station, Chris, clearly trying to scare me, sends me a text saying: "Welcome to Holborn". Never have I read three words that scared me so much - well apart from Mrs Pocket-lint telling me we were having a baby but that's a different story.

Why? Because it's clear that the idea of tracking your friends to see if they are nearby for a quick pint is just the beginning.

Chances are by Christmas, services will be appearing for a number of ways to use your location to "help" you in some way. Maybe it will be to allow you to track your running routes (like Nokia Sports Tracker), or perhaps big shopping centres might encourage users to sign up to track their movements around a mall to then put up rent on the big foot fall areas.

Maybe, and just maybe, coffee shops will use it to recommend you stop if there is a coffee shop nearby - Minority Report style. Location based advertising has been talked about for some time but never has it seemed so real. Yes, services to track people via mobile phone have been around for ages, but this is Google, free, and frighteningly simple.

Imagine walking past adverts on the road that change to suit your buying habits. Those location based advertising (LBA) conversations of a few years back probably now have a much larger database than ever before. Adverts could be geared towards the population demographic that physically walked past a digital board rather than trying to guess.

In the wrong hands this could be dangerous, especially if you can't protect your location (which you can in Latitude), but is it secure? Could industrious hackers find their way into picking up the location of everyone on the service? What better for a thief than to look at their phone and see the occupant of the house they're robbing is currently 200 miles away?

Or imagine watching your mate go to work, whilst you manually set your location as your office, whilst you pop in to visit his wife...

It's clear that geo-targeting our location is highly valuable to Google, to retailers, to anyone really as they will be able to use that data to sell you information or products based on where you at that time. There are, of course, data protection considerations, but it doesn't take much of an incentive to opt in, like a discount from your mobile phone operator.

As we all slowly but surely become electronically tagged like convicts on day release, our world will become more and more specific to us.

The days of lying about where you actually are could be over. Now when I say, I'm going to drop off the grid for a while, I really do mean it.