Not it is not a security. That was sorta the point of FinCen saying it was cash.
That issue is up for debate at all levels. In my home state it is a commodity, per the "unofficial" position of the securities division. If somebody would pay to get the "official" position in any state I'm highly confident many would say the same.
Unofficial interpretation from an
actual regulator:
A commodity is more generally defined under the laws as "a useful thing; an article of commerce; a moveable and tangible thing produced or used as the subject of barter or sale." Bitcoins would be "tangible," because each bitcoin is constructively possessed.
Federal law trumps state law in all cases of interstate commerce including international commerce.
Still cash is in fact a commodity, it does meet the definition. Cash is a special case of commodity that is subject to certain specific regulations that other commodities aren't. Cash is well defined and well understood and only subject to the regulations of cash and cash like instruments.
Bitcoin has been declared as "cash" which itself is a specific case of commodity and therefore only the regulations of cash properly apply to bitcoin.
When you swap USD for BTC the same laws apply as when you swap for USD for CAD. That is to say you need to know the source of funds was a legitimate business activity.
When you swap BTC for USD the above applies as well.
When you accept a deposit of BTC you need to follow the same laws that you would accepting a deposit of CAD or USD.
If you accept BTC from people and allow them to withdraw or send then you need to comply with the same laws you would as either a money transmitter or a bank.
If you lend BTC it is the same as lending USD and you should comply with the same laws as you would as a lender, however here you bear the risk of loss without the chance to recoup if you fail to comply. It is not a criminal act in and of itself.
This discussion could be extended to the peculiarities of every country though. The fact is you need to know your customer so you can comply with your own local laws and potentially theirs.