Those who are intermediaries in the transfer of virtual currencies from one person to
another person, or to another location, are money transmitters that must register with FinCEN as
MSBs unless an exception applies. Some virtual currency exchangers have already registered
with FinCEN as MSBs, though they have not necessarily identified themselves as money
transmitters.
Is it the end of unregistered exchanges?
This makes it more of a pain in the rear to operate any kind of Bitcoin/crypto-currency (or other virtual currency) exchange if you're based in the U.S., at least in a complying above ground way.