California's financial regulator has baffled observers by sending a cease-and-desist "warning letter" to the Bitcoin Foundation. The letter accuses the nonprofit of acting as an unlicensed money transmitter, even though its main activities are promoting awareness of digital currencies and developing the Bitcoin protocol client software. Did the Golden State's bureaucrats blindly send out letters to any organization it could find with the word "bitcoin" in its name? This much is clear: Rapidly evolving payment technologies are confounding traditional ways of understanding money.