'Some Israeli CS students'? That seems a little un-generous: the authors have published papers since the 80s, and one has a Turing award.

But I think the study you actually want might our study, which focuses on anonymity: http://anonymity-in-bitcoin.blogspot.ie/2011/07/bitcoin-is-n...

I might be biased, but I think we deal with most of the points JGarzik mentioned in our paper.

But we're not 'the Feds'; perhaps silverstorm was thinking of this story: http://www.wired.com/threatlevel/2012/05/fbi-fears-bitcoin/