The bombings in Boston are terrorist attacks, but it's far from clear who the perpetrator(s) may be, and between the talking heads on the 24/7 news channels and the compulsive nature of some on social media to express opinions on absolutely everything, the wisest response is to shut up until more is known.
Initial reports suggest the bombs, while coordinated, were not that sophisticated. That might mean a "lone wolf" bomber, but whether home-grown or foreign is unclear. A New York Post report — and that tabloid seems to have been operating in an alternate universe for a while, reporting several stories that proved untrue — even reported a Saudi national was in custody. The Boston Police promptly denied that, and also said no one was in custody. But that and other speculation led to some anti-Arab and anti-Muslim Internet chatter. And considerable concern among Muslims fearing they might be blamed. President Obama was right to warn against jumping to conclusions: many of us remember how the media assumed the 1995 Oklahoma City bombing was foreign terrorism, when it turned out to being an apologist for anyone, that's just American fair play: it was Patriot's Day in Massachusetts, after all. (But also income tax day, which could provoke some anti-tax radicals.) When there's evidence to discuss, the pundits and talking heads will have something to talk about. Until we know more, we should all just shut the [hell*] up.