DHS is specifically targeting MtGox, though. Right now they are doing it through the most convenient means, through shutting down bank accounts. I highly doubt they are going to stop there, though.
IMO, If they cant take down the exchange through seizing accounts, they will do it in court. This is also going to set a precedent on how they handle the other exchanges dealing in the US as well.
http://arstechnica.com/tech-policy/2013/05/feds-reveal-the-search-warrant-that-seized-mt-gox-account/