An article by Paul Pardi ("Philosophy News Service") at the Huffington Post sums up the significance of "new atheism:"
1. The arguments of Harris, Dennett, Dawkins and Hitchens tend not to be "new" and don't engage the actual arguments of liberal theologians.
2. As a social movement, they're nonetheless affecting the perception that the mass of people have on "the role religion is permitted to have int he public square:"
Political point scoring aside, serious talk that God is somehow involved in the daily workings of this world and that public life should be oriented toward pleasing Him and following His will has almost vanished. The New Atheism has succeeded in shifting broad attitudes towards public talk of this kind from one of mild amusement or irritation to one of outright fear and derision and has done so inside of just a decade.
3. An approach modeled on the natural sciences does not seem to be optimal for delving into questions of meaning and ethics. Which is to say (and this is not Pardi here:) that the history of philosophy offers multiple alternatives (e.g. Heidegger's phenomenology or Montaigne's "practical wisdom") to both scientism and theology to approaching these issues.