A few weeks after my last post on Bitcoin, the cryptocurrency was featured on EconTalk. From there it captured the imaginations of libertarian geeks everywhere. When I last wrote about it on March 12, one Bitcoin was worth 88 cents; today one is worth $17.14. There are now numerous startups dedicated to serving as Bitcoin exchanges, banks, e-wallets, etc. Notably, there are not yet any futures markets, which has led many commentators to quite reasonably cry bubble.