Many expected use cases require the user to send a certain number of coins as-of a specified time (specified as a reference block number rather than a date/time due to the fact that mapping date/times to block numbers could be nondeterministic and exploitable). As a consideration for the user it's better to let them specify what block their transaction is relative to, rather than just use the current block (the default behavior).
Moving to 0.0.1beta3, as that's where we're going to include the ability to specify refheight on the command line. These are most obviously implemented together.
Many expected use cases require the user to send a certain number of coins as-of a specified time (specified as a reference block number rather than a date/time due to the fact that mapping date/times to block numbers could be nondeterministic and exploitable). As a consideration for the user it's better to let them specify what block their transaction is relative to, rather than just use the current block (the default behavior).