The Nexus 7 has Near Field Communication (NFC), a fledgling technology that enables a wide range of wireless transactions. Such as? Well, waving or swiping your mobile device at a payment kiosk (don't hit anybody), and exchanging contact information by tapping two NFC-enabled devices together. The Kindle Fire, like most tablets today (including the new iPad), doesn't support NFC. Will the next-gen Fire?
To be fair, NFC isn't ready for prime time. There aren't enough NFC-ready mobile devices, kiosks, checkout stands, and smart posters (e.g., wall posters, billboards, and even magazine ads with NFC tags) to make it mainstream. That may change soon, however. The Kindle Fire, a device built largely for buying stuff (at least from Amazon's perspective), seems a natural for NFC.