Timelock Transactions
nLocktime has always been standard and is used to prevent fee sniping. 

OP_CHECKLOCKTIMEVERIFY is currently not implemented and is not enforced. 

A non-standard transaction can be mined by a miner, but will not relay around the normal peer to peer network. A transaction who has a nLockTime which has not been passed is invalid, and won't be relayed or included in a block until this time has passed.