Here's the thing that bugs me about the bombing in Boston (besides the obvious.)
It really doesn't fit a pattern. Or actually, it fits a couple of patterns imperfectly, that are more or less mutually exclusive.
Islamists (and other religious/political terror groups, like the IRA) historically make a point of claiming responsibility for their work. As far as we know, there haven't even been dubious claims of responsibility for this one. So even though the M.O. of a low-tech IED set to maximize random carnage fits the profile of AQ and their wannabes, nothing else really does. (Some might argue that these guys look a little...swarthy...but so does Gino. So do I after a week at the beach, for that matter. Seriously, the only thing that we can say about the suspects from those pictures is that they are not sub-Saharan Africans, and at least one of them isn't east Asian. They probably aren't Swedish, either.)
On the other hand, our home-grown politically motivated terrorists do tend to like this particular week in April, but they also tend to go after government buildings. Avenging Waco seems like a hell of reach, too.
What I am struck by, though, is the ingenuity (please don't mistake my word choice here for admiration or approval) of the timing and the setting of the attack. And to a lesser extent (because it might have been serendipitous) the physical nature of the blast damage.
I'll take the second point first. Based on the injuries suffered, it would appear that the blasts and shrapnel radiated outward along the ground. That's why so many people lost legs and feet, and probably why one of the casualties was a little boy. It makes for a horrific scene. In some ways, grievously injuring a couple of hundred people is more of a spectacle than killing a handful.
Which brings me back to the first point. The bomber(s) weren't targeting the marathon. They were targeting the crowd on the side of the course. At the finish line.
In other words: a crowd of people in a place and time where nearly everyone had their camera out. Add to that the delay between explosions was too short for the old tactic of waiting for the first responders to arrive, and setting off a secondary explosion. But it was just right to be certain to be caught on any number of camera phones being whipped out after the first one.
Maybe this was political, or religious, or some warped version thereof, a la Eric Rudolph. But really, this just looks to me like someone wanted to really hurt some people, and for the world to see it.
Needless to say, I sincerely hope the bastard(s) responsible for this are brought to justice. But I think we should be ready to find the answer to the question "why?" very, very unsettling.