Well Danny, I'd like to relate a few things to each other if you don't mind;
I don't know for sure whether these things are happening that much more often than, say, 10-15 years ago.
What did happen/evolved in the past 10-15 years is the ever increased speed and ease of access to information, which greatly increased our "awareness" of these incidents.
What I find disturbing about this act of violence/terrorism in Boston is the way it is hugely discussed by the global media.
By no means I want or am trying to trivilise this horrible incident, but these "incidents" happens almost every day in multiple places in the world like Afghanistan, Syria or Iraq. There it aren't incidents anymore, but rather daily business.
Many of these incidents are even more gruesome, if you wish or dare to relate them to each other.
Even back in the days of the IRA in Ireland something occured on almost a daily basis.
Did we care that much then? Or do we now? Don't think so.
Now some lunatic does this in the US and now we're all supposed to panic and fall over each other to be first to scream out it's all disgrace and shame? Sorry, no.
The global media gives this incident way too much attention and "credit".
I hope they get the guy who did this, so that the victims didn't die or got injured in vein.
Else, we should move on and get back to focus on the global financial crisis. (for example)
This whole same story applies to North Korea.
Important things are happening in the world in relation to the financial crisis, but we're made to believe North-Korea and the Boston bombing are much more important.