I've noticed that if you have ANYTHING saved in Passbook, whether it's a coupon, loyalty card, anything, that any time your lock screen is activated, Passbook also activates your Geo Location (via location services) and checks to see whether you have anything in Passbook that it needs to display (based on where you are). The real problem with this is that simply turning on your screen is a major battery drain. What most people don't realize is that your screen turns on a lot more than you think. For example, some people have their email setup to display every time there is an incoming email. So if you were to get 50 emails a day, that's 50 times that your screen comes on (and 50 times that Passbook loads location services, in order to see if you are near anything stored in your Passbook). Couple this with how many more times your screen activates because of any other apps that notify or alert you via the lock screen and you have Passbook activating location services 100 times a day. You can test this by placing any coupon etc in Passbook and then watching the top of your screen any time your screen comes on. You will see the blue triangle light (indicating location services is on). Now go back and remove EVERYTHING from Passbook. Now when your screen comes on, no more blue triangle and no more location services checking to see where you are.