So be careful, not properly registering as a Money Service Business, Money Transmitter, Bank or Financial institution is why these exchanges including MtGox keep getting shut down and seized by the authorities. It's not like there is some huge conspiracy against them, it's just laziness on the part of the owners.
Mt.Gox wasn't shut down/seized by authorities. Pure FUD.
Their Dwolla account was locked. Dwolla account locked != shutdown/seized.