The article in the link below describes an investigation or test related to the tracking of mobile devices. By making use of ‘publicly’ available information, among other things, from the sensors of your phone. What sensors does your mobile device actually carry?

Well, in any case in the better equipment you’ll find, for example, these sensors:

• Acceleration sensor (accelerometer) measures changes in the speed and direction of the phone.
• Gyroscope: helps the accelerometer to establish the ‘line of sight’ of the phone.
• Magnetometer: Helps the gyroscope and accelerometer with the orientation in relation to the earth’s magnetic field. Like a compass.
• GPS – The Global Positioning System determines the position of the telephone using sate.
• Barometer: measure the air pressure. Used for determining altitude.
• Thermometer: measure the ambient temperature.
• Hygrometer: measuring the relative humidity of the air.
• Proximity sensor: with an infra-red led, the phone ‘sees’ the proximity of your ear. So it can switch off the screen…
• Ambient light sensor: measures the ambient light, so the brightness of the screen can be auto-adjusted.
• Fingerprint Sensor: optical or capacitive scanners ‘to see’ or ‘feel’ the pattern of your fingerprint.
• Camera: to be used for the most diverse applications, including heart rate measurement.
• Microphone: Yes, really. The mic definetely belongs in this category. Siri is listening.

Here’s the article on The Register:
Boffins crack location tracking even if you’ve turned off the gps

Now, is this bad? It depends – as long as you’re aware what information is gathered (and therefore may be shared) by your mobile device, you can choose whether to switch it off, leave it at home, or take it with you. However, who believes oneself unobserved, might be in for a disappointment. Real privacy is becoming scarce.