Originally posted on 9to5Mac:
In line with our report from last week, Apple has flipped the switch in its Apple Store app to allow for customers to check availability for the new iPhone models at Apple Stores. The process is similar to the one for Personal Pickup on Apple’s online store.
To check for availability on the iPhone and iPod touch Apple Store app, navigate to the buy iPhone page, add your iPhone to the cart, then choose “Check Availability.”
The app will show you a list of your favorite and nearby stores. With Personal Pickup, you can order an iPhone through the app and then pick it up at your local Apple Store. With iPhones now shipping in October, this might be your best bet at soon getting an iPhone 5s.