Here are some of the better links I read today. They're not necessarily about what happened, but what it means and how we react.
I loved Leigh Montville's Marathon recollections. He captured the spirit and fun atmosphere of the day. (My roommates and I played a marathon game years ago. I would explain it, but you had to be there...)
EDSBS wrote about the true terror of the aftermath and how we do move on from these things. Like him I am in Centennial Park regularly and never give the bombing much thought. My kids run around that whole area without a care in the world.
Some well-intentioned BC students created the Last 5 walk/race to support those who didn't get to finish the race and those who were impacted. Thousands signed up but the City is asking them to postpone the event to a later date. The crowd control issues, the safety issues, and ongoing investigation all take priority at this point. I am sure when it happens it will be a great event.