Solidarity to the people of Boston.
Erik Rush, a regular contributor to Fox News, had this to say:
President Obama doesn't yet know who did it, but Erik Rush does. He's named his enemy because he knows he can sell a lot of fearmongering articles to Fox on the back of this atrocity in order to profit from the post-9/11 Islamophobia which is borne by many Americans today. He wants to make his money off of Boston's dead. There's a term for creatures like him, and that term is carrion fowl.
A news source suggests the bomb is probably domestic. This doesn't rule out a Muslim as there are plenty of Muslim Americans, but it does make it even more likely that the bomb is the work of some Neo-Nazi or disaffected sociopath.