Dwolla was a major funding source for individuals who need to transmit dollars to the MTGOX Bitcoin trading accounts. The MTGOX account at DWOLLA a US based company was frozen at the request of the DHS supposedly over concerns of money laundering. It was incorrectly reported in several areas that MTGOX was directly targeted by the DHS but fortunately their influence as of now doesn't reach that far.
DWOLLA isn't the only game in town for buying Bitcoins or even transferring money to exchanges though it was a popular choice. This is the second major USD to Bitcoin exchange operation shut down in the last month as Bitfloor.com 's bank account mysteriously got shutdown without warning. Though there is not indication that action was due to government interference.
So the question on everyone's mind seems to be is this the start of the Bankster owned government crackdown? Well we are optimists here at Team Bitcoin and do not put much faith in the ability of any regime successfully regulating an idea who's time has come.
There are enough talented folks working on Bitcoin projects that can and will hopefully stay a step ahead of regulation attempts too early in the game.