Hi Mike 

Not sure if you've seen it, but here is how we do NFC right now http://www.youtube.com/watch?v=DGOMIG9JUY8 with XBTerminal. 

For now this is just an NDEF URI message with Bitcoin URI inside, and then transaction itself propagated to the network by the phone using it's own Internet connection. Far not ideal, but even this is supported only by Andreas' Wallet, so we cannot move ahead alot really until other wallets will have some support in this area.

As you see - it's taking just few seconds, most of which is manual payment confirmation. Btw, ignore my first screen tap, where I'm selecting wallets - it's an unlikely thing to happen IRL to have several wallets installed at the same time.

​Also, I think many people may not know about Oyster cards, so this might need little bit of explanation. And btw, have you been to London lately? Oyster readers now accept contactless cards directly along with Oyster cards itself. I wonder if eventually in future we could add bitcoin support into that system directly, without hardware replacements.

I cannot put much into the actual protocol discussion, but I'm happy to provide feedback on the side of actual POS implementation needed and testbase if required.

Have an ​idea - it's a good thing to cap confirmationless payments, but the actual cap value definition can be tricky considering Bitcoin volatility. Inless you want to tie it to some external price definition thirdparty service it could be tied to transaction fees. I mean - if with Bitcoin v0.9 transaction fees will become really floating, and it should eventually reach equilibrium that will reflect some real world value. Probably a tiny value, but probably also rather stable value. So confirmationless payment cap may be defined as <current_average_transaction_fee>x10000.