hi,I think the bitcoin should be a tool for  pay,such as gamble ,vending,shopping guns ,and so on....

@CornedBeefHash Thanks and yes, that's a good point. One of the reasons I'm putting this list together is to identify that kind of issue and decide how it could be handled. I will discuss all of this in a blog and post a reference to it in the "Press" section here.

All retail transactions have this issue of waiting for confirmations because the expectation is that they will be fast. Briefly, my thought on this is that bitcoin is no worse and may actually be better than credit cards in this respect because the actual payment of a credit card charge doesn't happen until the merchants transactions are "batched" at the end of the day. During that waiting time, the card holder can renege on the payment. Also, I think as a practical matter, double spending attempts will be relatively few and far between because a) most people are honest and b) you basically can't get away with it in the long run.

But it remains is an interesting problem to try to really fix.