Ben Goldacre is very concerned about how easy it has become to track people via their mobile phones without their knowledge.
"Here’s a scary story. You can track anybody’s movements through their mobile phone, all you need is five minutes access to their phone. You receive two text messages, and send one in reply, then delete the evidence, and bob’s your uncle, your target would never know. On Radio 4 today I pointed this out to one of the companies that offer this service. Their response is, essentially, that this had not occurred to them as being a problem.
I don’t get angry easily, but to my mind, this is a sinister story, and the phone companies are failing to protect your privacy, by giving away your location to anybody on the flimsiest of “consent”: one text message."
The 12 minute radio extract that he refers to gives a clear airing of the issue.
Update: Ben had an article in the Guardian on Saturday which went into a little more detail about his concerns.