I have only seen a few post that document the distance in which the proximity sensor activates and deactivates the screen. My iPhone 4 shuts the screen off between 3/4 - 1 inch away. I had remembered that the other three versions of iPhone I had where in the range of 2 - 3 inches. My mother still has a 3GS running the most current version of 3.0 software. I have not had the chance to test it but I know the distance to be far more than 1 inch. If you were to measure the distance of the earpiece from your ear with your cheek touching the screen, that distance is very very close to the 3/4 range. Simply move the phone above your ear slightly and now that distance is closer to 1 1/4 inch. I have done the reset all settings, reset network settings, power off, hard reset, restore to factory plus restore from backup, and restore to factory then reset all settings and setup as new phone with no restore from backup. At various points along the way I tested the proximity distance and it never once changed. The very first night I used the phone I did notice it flickered during my phone call as it did in the video referenced in this thread. I have not seen that happen since all the resetting and restoring but it is still EXTREMELY easy to reactivate the screen during a phone call with the phone placed between your shoulder and head, casual phone conversation (I don't like to jam the phone tight to my ear as it gets hot and uncomfortable), and laying in bed on the phone. I suppose if you use the two finger death grip to mash the phone to your ear, it seems to work fine. BTW - I purchased 3 iPhone 4's and all three of them have a prox distance of 3/4 - 1 inch. Please post your measurements. I would be curious to know the distance of all the previous models with ver 3 software and version 4 software.... I am praying this is a software issue. Different prox switches have different sensitivity ranges and there is only so much software can do.... A 1.7 million phone recall would suck. BTW#2 - I still love my iPhone and every Apple product I own.