Bitcoin is currently being used as a publishing system due to a design feature/flaw. That flaw threatens the viability of Bitcoin as a currency.
How so?
Some folks have expoited that feature/flaw to publish Wikileaks cables and pedophile porn links in bitcoin's blockchain.
Of course, that's a problem. It may attact some aggressive behavior from governments, well before it reaches a maturation.
Bitcoin is an open source software system. That means nobody owns it.
Up until now, it's been used as a decentralized currency system.
Why?
Bitcoin makes it possible to make non-reversible decentralized transactions on a global scale.
It's visibility as a currency has been good for bitcoin. Speculation has driven up the price of bitcoin to a market cap over $1 billion.
Boston is a reminder that: Open source warfare doesn't ever go away.
It can be revived with a terrible suddenness, as we saw at the Boston Marathon.
The grievances and motivations for attacks never die. They can always find a corner of the Web to fester and grow, in groups too tiny to ever control.