user134: If I accept bitcoin for payment, provide a new address for each payment and make it clear to payers that I consider payment complete only after waiting the ~10 minutes for a confirmation, is there a technical reason why I can't immediately spend the bitcoin without waiting for the confirmation? Is it impossible to spend it because the address has no transactions in the block chain?

user85: There is no technical reason you can't spend it immediately. A transaction that is dependent on an unconfirmed transaction should be accepted by the network and should eventually make it into a block.
You will almost certainly have to include a transaction fee with the second transaction in order to get it accepted into a block immediately. Otherwise, you will be waiting some time before the second transaction gets committed into a block.

134: <p>If I accept bitcoin for payment, provide a new address for each payment and make it clear to payers that I consider payment complete only after waiting the ~10 minutes for a confirmation, is there a technical reason why I can't immediately spend the bitcoin without waiting for the confirmation? Is it impossible to spend it because the address has no transactions in the block chain?</p>
 85: <p>There is no technical reason you can't spend it immediately. A transaction that is dependent on an unconfirmed transaction should be accepted by the network and should eventually make it into a block.</p>

<p>You will almost certainly have to include a transaction fee with the second transaction in order to get it accepted into a block immediately. Otherwise, you will be waiting some time before the second transaction gets committed into a block.</p>
