A Bitcoin conference in New York last week drew a motley crowd. There were the expected wide-eyed believers in the digital currency, earnest entrepreneurs building Bitcoin-related businesses, and somewhat more skeptical venture capitalists — but also traditional banking lawyers and anti-money laundering compliance consultants whose services are in hot demand. Startup executives complained about the difficulty of getting (or keeping) bank accounts and state money transmitter licenses. But the technology shows great promise and demonstrates that it is possible to send money as fast and as cheaply as email, even if banks running on legacy systems cannot.