Wow, nice find. I hadn't thought about tracing the cell phone before, of all things.

Practically, it seems like a stretch to try and look at GPS logs through a carrier and prove that someone was at a bank at a given time. It says the precision is down to 2 hours, so you can theoretically get to a bank, not make/receive any calls, and get back before that 2 hour window and nothing would ever be recorded by the cell towers. If anything, this only proves that you were in a geographic region. Plausible deniability?

Also, this problem goes away completely if you leave your cell phone at home. An easy trick to adopt for the Joes looking to buy Bitcoins anonymously.

True, but my point is given a large data set we find surprising ways to trace it back to people.

So at some point I would expect goverment/people to crack open the bitcoin data and stat mapping it to people and looking for trends.

I don't think that is specifically a bad thing but you should conciser it before doing something foolish with bitcoins.

I definitely agree that someone who buys Bitcoins needs to think about how identity is tied back to them, but so far it's not a convincing point that Joe is at a high degree of risk if he's cautious. Those points need to be debated specifically, and not from an abstract or high level. The cell phone example was the first I heard of that, and a really good example. But it's not going to break anonymity.

It sounds way too hand-wavy to me to say things like "Well, Bitcoins.. It's a con.. the government will find Joe, somehow.. Be afraid!"

So far, my point stands that you can remain completely anonymous while buying Bitcoins. The article started out with fear mongering, and so far, I'm unconvinced that it has any substance to it. To call it a "con" is sensationalism at best.