There is the concept of green addresses (https://en.bitcoin.it/wiki/Green_address) to solve this. Basically if customers use a wallet that the merchant trusts not to commit a double spend then they can safely accept a zero confirmation transaction. MtGox and Bridgewalker (https://www.bridgewalkerapp.com) support this so if you trust them and your customer uses them then you can accept the transaction immediately.

Of course for something like a cup of coffee or even a purchase for $80 worth of clothes I think most companies would be fine with accepting a zero confirmation transaction and taking the risk as it will be far less of a cost then shoplifting and will be less than the 2% they currently pay on every credit card transaction. If you are buying a $1000 laptop then maybe they make you hang out while they explain the features and wait for a single confirmation.