and GPS can be used for a number of things, but have you considered them being used for fraud prevention? That's an idea just announced by Visa Europe.
It's pure common sense: the assumption is that if the smartphone and your credit card are in close proximity, you are most likely using the card, even if you normally live in Belgium and are showing up in New York City.
In partnership with a company named ValidSoft, Visa Europe is looking into the idea. If things work as planned, there will be less false positives where a credit card company thinks "someone else" has your card or card number and is using it half a globe away from where you live.
Of course, this won't fix the issue where you might be ordering something from a website in Australia and you are in California, but it should reduce the number of times you see annoying calls or even locking of your credit card when you are on vacation.