The book is The Eliminationists: How Hate Talk Radicalized the American Right. It's by blogger David Neiwert and it's what helps put the radical path of right-wing rhetoric under Obama into proper, and historical, perspective. It give much-needed context regarding how that brand of hate speech has been mainstreamed via talk radio and Fox News, among others.

Reviewing the timely new book in American Prospect, Elbert Ventura writes:

Neiwert's commentary is depressingly timely. While paranoid and anti-intellectual rhetoric has long defined conservative media, the latest strain seems to be louder, meaner, and more pervasive. Where once the kind of hate talk Neiwert describes was confined to the fringes, it's now part of daily programming at Fox News. To a distressing extent, much of mainstream right-wing culture and politics is predicated on hatred and exclusion. Hardly a day goes by that an epithet isn't hurled against Hispanics, Muslims, immigrants, gays and lesbians, and other bêtes noire in conservative media and the right-wing blogosphere. And let's not forget the greatest enemy of all: liberals. More than low taxes, traditional values, or a hawkish foreign policy, hatred of liberals (as opposed to mere disagreement) is the one true unifier among conservatives. Neiwert sums up the right-wing mentality by citing a line from Benito Mussolini to a left-wing critic: “The democrats of Il Mondo want to know our program? It is to break the bones of the democrats of Il Mondo.” For many conservatives, the goal isn't so much to enact conservative policies as it is to vanquish the liberals in their midst.

UPDATE: Many thanks to Glenn Beck for pretty much proving this radical-rhetoric point within hours of this post. See, Americans are on a Holocaust-like list and the government is coming to get you.