I guess this is where we are still in a wait and see mode. The US govt. seeks to control all and smash anything threatening its ability to dominate economically. Just look at the last 15 years as a small sample. Yes they have not begun targeting CampBX and exchanges directly, but I do feel this is their first step in attempting to halt or disrupt Bitcoin. This though, is getting slightly off topic and discussing politics here never produces a winner.
The DOJ doesn't do this stuff by piecemeal. They didn't shut down Megaupload.com one day. Freeze the banks another day. Arrest him another day. It happened all at once.
MtGox is on a .com, they could seize that anytime they want. Japan is more buddy buddy with the USA then New Zealand is. If they wanted to go after Bitcoin, every Bitcoin .com would be gone. CampBX would be gone. Bitpay, BitInstant, would be shut down, banks seized. They've both American companies.
The DOJ isn't after Bitcoin. It doesn't even make sense to go after them. Cryptocurrencies are here to stay. The genie is out of the bottle. They're better off tracking Bitcoin, keeping tabs on it, then pushing it further underground. Bitcoin isn't a threat to the USD. People are dreaming if they think it is. The DOJ will cut a deal with MtGox, let us have access to all the logs (website and transactions) and we'll leave you alone. Considering MtGox is telling people it will cost 25M to become legit in the USA (and they're planning to do it), they'll play very nice with the DOJ going forward.
This whole event was actually good news. People leaving MtGox for other exchanges. The sooner that happens, the better.
AFAIK, LEOs haven't yet had a test case on whether or not courts will agree with BTC classified as currency. This is that test case and could lead to other consequences if a clear precedent is set, inside and outside the US. Hopefully, Gox's defense team will directly challenge that particular point of contention instead of caving and hoping someone else will do their work. Odd as it sounds, I think this could be decided by the Supreme Court. What is currency, and how does the USG reconcile its laws normally reserved for USD to new alternative "currencies"? Can FinCEN and (for whatever fucked up reason) DHS regulate video-game currency as if it's the holy Dollar itself -- Bitcoin, Litecoin, Ripple? Can USG bureaucracies run around fining and shuttering any exchange which hasn't spent millions in USD? Is BTC taxable as currency, or a commodity?
I view this as recon, not war, but if given a crack, the USG might go through it like a floodgate going down.