While I would hope that this would be true, I do not believe that Bitcoin is yet ready for POS acceptance outside of mom and pop shops with current services.
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Having worked POS development and support for a 2000 location corporation, I can tell you that Bitcoin can be made simple and employee idiot proof (and theft-proof too, since it is the customer creating the transfer and not the retailer). Unless they are using old-fashioned phone line machines, the company headquarters will already have data lines up to locations for POS credit card transactions which are processed through their custom terminals and datacenters, and the datacenter has high speed links to the backend servers for credit card companies. It's not much to add another payment option to software-driven terminals. I'm sure people here have used credit cards at Starbucks for example - with a card swipe you are through in 10 seconds.
The company would begin a transaction by creating a unique address and expected BTC payment in it's database, and push that to the POS and customer (with a 2D barcode on receipt or a POS display for mobile phone, etc). The transaction would be closed or finalized when the payment address gets its bitcoins, and an "all clear"/processed signal can be returned to the register. The database backend can use heuristics to determine risk in taking a 0 confirmation transaction, such as the transaction being distributed to a majority of nodes, an adequate fee to ensure inclusion, and balance and sending history on that address that might indicate a double-spend attempt. Considering that retailers have to eat credit card fees, and losses from stolen and disputed payments, etc, a non-reversible free bitcoin payment is like a godsend. The only big hurdle for Bitcoin at the POS is you have to wait for some confirmations for 100% fraud-proof money.
One thing in a retail environment, customers need to know how much the purchase cost is in BTC before making the purchase. To that effect, we need not a more stable exchange price, but retailers that are willing to set a long-term BTC price instead of simply looking up the current exchange rate. If customers know that 1 BTC is always worth a hamburger, expanded retail presence can actually stabilize BTC exchange rates.
