大象传媒

If you鈥檙e about to enter a coffee house in San Francisco it's a signal that you鈥檙e probably not at home in Tooting.

A year or so ago there was a great website called Pleaserobme.com. It took feeds from Twitter, Facebook and all the rest and drew attention to people who used the social networks to announce when they were out. They might be away, they might be gone for hours or days, but they鈥檇 made it very public that they weren鈥檛 around for a while.

Status update: the back door key's under the bin

It would be tough to find documented cases in which thieves had found their quarry using social media, they鈥檙e terrible at filling in questionnaires about where they found their victims, but certainly last year there was talk of insurance companies increasing their premiums for people who wilfully make their location available everywhere to any passing crook who鈥檚 online.

Pleaserobme feels the point has been made. Unfortunately the issue of people giving thieves an open invitation to break in and help themselves is far from closed.

It鈥檚 likely to be highlighted again as General Motors brings its On-Star communication tool into an alliance with Facebook, assuming the rumours are true. Your car will be able to help you update your Facebook status. But can it do it without bleating that you鈥檙e away from home, too?

Location-based networking, as it鈥檚 called, has many uses and benefits. Services like FourSquare will end a Tweet telling everyone where you are which is brilliant if you鈥檙e, say, between meetings and would like to see if anyone鈥檚 around for a coffee. 鈥淚n Trafalgar Square considering a coffee鈥� might well get a response from someone who鈥檚 in there and equally at a lost end. There can be many reasons for wanting to know where your friends are.

Likewise many cameras and phones offer geotagging of their photos. This means the picture will carry little bits of data on when and where you took it, so that sort-out of pictures and the wondering-where-the-thump-you-were-when-you-wore-that-jumper-in-front-of-that-mountain ritual can become a thing of the past; click on it and it鈥檒l tell you it was Milton Keynes, last week, or whatever.

How can I protect myself?

The snag is that people are starting to leave these services on by default. If I had malicious intentions then yes, I could take your automated announcement that you鈥檙e about to enter a coffee house in San Francisco as a signal that you鈥檙e probably not at home in Tooting. Even when people switch the automatic notifications off, though, a handful still insist on announcing when they鈥檙e about to lock up and go on holiday.

I suppose there are two ways around this. The first is not to leave the house empty in the first place, although although of course it's not always easy with a busy 21st century lifestyle. The second is of course to watch what you Tweet, Facebook, LinkedIn and otherwise announce to the world 鈥� and if your home鈥檚 going to be vulnerable, don鈥檛 tell everyone.