Right now, there is a solution.  As long as both the merchant and customer use the same ewallet provider, transactions can be instantaneous.  MyBitcoin works this way already today.    Similarly, another solution might be simply to advance some amount to an account with the merchant or with some other intermediary.  Consider if the mobile point of sale vendor Tabbed Out were to add bitcoins as a payment method, for example.  They would hold your coins in their wallet so those coins would be spendable instantly regardless of which restaurant you dined at.  With those solutions, however, you have the drawbacks where you must extend trust to an intermediary and lose some privacy.

One other idea includes a pure bitcoin method where low value transactions might be allowed on receipt by the merchant with no confirmations.  This method assumes however that there are listening posts on the network that would monitor for double spends and alert the merchants after any double spend attempts were discovered.

Additionally, there have been reports that work is underway to integrate bitcoin with the Open Transactions platform to allow transactions that are both anonymous (as far as the merchant knowing the buyer) and also are instant, requiring no confirmations. This too requires pre-paying bitcoins to the OT account that will be used for spending.