I'm pretty sure I just witnessed/participated in the future of all retail.
I walked into the Apple store and they were absolutely slammed. All I needed was a iPod connector because I'm pretty sure my wife is trying to drive me crazy by losing them all. Any way, instead of waiting and waiting for someone to help me I pulled out my iPhone, went to the Apple Store app. It recognized that I was not only in an Apple store it knew which one. It had an option to scan the scan bar. I select it, it scans, I pay, email myself a receipt and walk out of the store product in hand without getting brained by security.
I just have to say, wow. Not that I hate interacting with people, but when I'm in a hurry and don't want to hang out in a store that busy it's amazing to basically be able to grab what I want ring myself up with my own phone and be done.