Probably just fine; I'm sure they had to apply for a regular banking license anyway, and banks are exempt from money-transmission regulations.
However, BankSimple is not a "bank." We partner with chartered banks who provide FDIC-insured products, leaving us free to concentrate on designing the complete consumer banking experience, via the web and your smartphone.
What implications this has on their regulatory requirements, whether banking or money transfering, would be interesting to discover.
Piggybacking off of someone else's banking license isn't trivial, but it beats the delays and capital requirements associated with starting a bank.
Of course, they still have to deal with all the internal industry regulations in order to offer things like ATM cards that work across ATM networks. Those aren't regulatory requirements, but when you're dealing with VISA-size entities they might as well be.