It's probably been mentioned before, but I just discovered a way to see the proximity sensor in action.
Go into the Phone app, and make the Voicemail tab active. You will then be able to cover the sensor, and the screen will turn off. It's quite interesting to see how sensitive it is - mine kicks in when my hand is about 8cm away from the sensor.
Go into the Phone app, and make the Voicemail tab active. You will then be able to cover the sensor, and the screen will turn off. It's quite interesting to see how sensitive it is - mine kicks in when my hand is about 8cm away from the sensor.