So you go to meze grill and buy a sandwich, to help the economy, I think you are doing more harm than good. The bitcoin system is too slow to use on less than 5 minute transactions. If you use a wallet, you are not using bitcoin, you are using a centralize play money site. Paypal, dwolla, and poker sites are examples of play money sites based in U.S. dollars.
Meze grill is based in dollars. It is basically an exchange. You buy a sandwich, he gets the bitcoin, he sells the bitcoin on mt gox to buy lettuce. The transaction could have gone, you have bitcoin, you sell bitcoin for $, you go to Meze grill and pay in cash. So meze grill is an exchange, why is that bad? It is bad because the transaction is small 0.5 BTC. It is just going to load up the system with small transactions.
Now I love the idea that Meze grill offers to sell bitcoin (maybe buy too not sure). Thus you go in with $100 and buy 10 BTC. Thus they are a real exchange. It just hit me you can easily have a bitcoin atm. You stick a usb stick in the atm, you put a $100 bill in it, a wallet .dat is added to your usb drive. You can also sell, put a wallet.dat on the usb drive and out pops some cash.
This just made me think of another idea, bitcoin block chain that holds wallets not bitcoins. Your wallet is stored on the block chain and a monthly fee is added to your wallet, if your balance goes to zero it is deleted.
I is nice to have hundreds of exchanges. Thus if one goes down you can use another. But, I forgot what I wanted to say. But still like the post so I will fix it or delete it later.
The Bitcoin system is more than fast enough for sub 5 min transactions, you don't need to worry about confirmations unless you think your customer is going to preform a double spend attack to get out of paying for his sandwich.