I'd like to know if there are transactions that can only take place at some predefined moment. In principle, it should be possible to use the parameter nLockTime to wait for a particular block number:
This could be useful in certain contracts, but replacement is not as yet supported:
In any case, it seems you still can, in principle, create a simple, unreplaceable transaction with a wait time.
Is there any example of such a transaction in the blockchain? If not, would it be accepted by the standard client or would it be necessary to convince one miner to include it in one of his/her blocks.
UPDATE: Opened a discussion in https://bitcointalk.org/index.php?topic=131443.0 to delve further.