This is the thing that worries me the most about Bitcoin and other cryptocurrencies--because I want them to succeed--there are myriad laws surrounding money transfers, especially electronically. There are tax implications, as well. There are also huge trade agreements internationally--and even intranationally--that come into play, as well. Banks and credit card companies currently handle most of the legality of these things, but with cryptocurrencies, there are no banks--these are essentially cash transactions.
I expect more and more folks will start to "discover" the real legal implications of some of these types of applications. I'm sure we'll see some story or what have you, and we'll all cry foul, even though the laws have been in place for many years and we mostly (albeit somewhat unknowingly) abide by them.
I also expect that folks will "discover" why we have central banks for currencies, and why Alexander Hamilton was a Smart Guy.
While cryptocurrencies are new, the problems they'll face aren't--in fact, we've solved these problems mostly in developed countries. They still exist pretty readily in developing countries, though. What happens when we start selling securities based around cryptocurrencies, such as derivatives? If you think the SEC will allow Americans to buy, sell, and even discuss securities openly, you are out of your mind.
What about money laundering? When/if you ever work for a bank or an investment firm in the US, you'll take some training around money laundering (there are even tests at the end). The SEC (allegedly) holds these firms responsible for spotting, reporting, and stopping money laundering schemes. What happens when money laundering happens over an exchange? How will that be handled?
Sorry for the long-windedness...your anecdote just got me thinking.