BLN doesn't replace LED to me though. Sometimes BLN lights up randomly on my Nexus S though rare. False alarms. How do I tell the difference between a text and email? LED colors help with that. I used to have a color for gmail, work email, twitter, Facebook, and texts, and low battery on my Motorola Milestone.
Does the paid BLN app allow you to blink certain buttons only? Say the Home button? Or the search button only? Or two buttons? That would be cool to tell the difference between different notifications.
NFC is overrated. Ok, so you can swipe your phone across. What if you want to pick a credit card? I use a certain card for gas, a certain card for groceries, certain card for shopping. I'd have to go into my Wallet app and pick a card. Might as well pick a card from my wallet just as fast. Plus, the problems of losing your phone become multiplied by 100x now that your CC is linked to it.
Honestly, credit cards are DAMN fast already, especially with stores like Target getting the message that you shouldn't have to sign the damn transaction everytime for small purchases. I don't really see the NFC advantage here. Plus, knowing the US, adoption will be slow as fuck.