Is Bitcoin suitable for fast transactions, eg in shops? Let's say all usability problems were solved. I'm imagining something like shops with tills that present QR codes for the amount and payment address for a transaction, and mobile clients exist that can scan them and present and easy Pay / Do Not Pay choice. So paying in a shop by Bitcoin would be no harder than credit/debit card, or even cash.

What limitations inherent in the Bitcoin protocol and network might prevent this from working? I'm thinking of things like:


Network latency (transaction being received by the shop) holding up queues
Poor mobile reception meaning shoppers find they unpredictably can't send money
Lack of confirmations before the customer leaves meaning shops may sometimes lose payment


I can see this being less of an issue in slower transactions, eg pubs, bars, restaurants. Are the above problems likely to materialise, and if so, are there any other types of transaction that might be affected?
The time for when a block has been confirmed is the main issue that seems to arrise. The coffee shop problem (I want my coffee now but this may take 10 minutes to confirm payment)

The mobile reception issue could be resolved by allowing restricted open access with on-site wifi service

There are third party services which may help this very effectively (www.flexcoin.com)

Also SolidCoin offers 3 minute blocks and may be substantially more elegant if a third party service was chosen not to be used for small transactions.