I didn't catch who was speaking on the phone to MSNBC, but he said this kind of violence can be attributed to what he called "the Obama effect," basically racist nutjobs being driven insane by President Obama.
I'm somewhat optimistic that there are fewer of these people than one might fear, but...
I presume that this refers to the Holocaust Museum murder, but it could equally well refer to the killing of Dr. Tiller. Cast your mind back to the nineties, if you can (if not, Google the Oklahoma bombing), and you might agree that there's a tendency of extremist aggressors to get more desperate when societal trends don't go their way. These people are not many. I sincerely hope that no talk show host or blogger or columnist tries to wind them up the way they did before the Oklahoma bombing.