It might be harder for authorities to monitor bitcoin transactions. But, as the very fact that this HN article exists illustrates, the blockchain is a public record that's available for anyone to monitor, analyze, cross-reference with other sources of data, etc. Particularly for large movements like this, I'm inclined to say that it would be downright foolhardy to assume that BTC transactions are anonymous.
It might be foolhardy to assume that BTC transactions are anonymous, but that doesn't mean that it wouldn't be EXTREMELY EXTREMELY EXTREMELY difficult to figure out who was involved.
Here’s who (probably) did that massive $150,000,000 Bitcoin transaction (washingtonpost.com)
From the article: "Who was responsible for the transaction? I asked Sarah Meiklejohn, a computer scientist at the University of California, San Diego, for her thoughts. She's the author of a recent paper demonstrating that sophisticated analysis can reveal a lot of information about who is responsible for Bitcoin transactions. She has combined a large database of Bitcoin addresses tagged with their likely owners."
Case in point: Supposedly the money from a lot of cases of major Bitcoin theft is still sitting in the same wallets. Implication: The thieves are having a hard time figuring out how to spend the money without outing themselves.
