The Pew Forum survey has shown that nones have now grown to 20%, and the Secular Coalition points out how this is going to have to change politics in the U.S. Among other things: we've gone from 15% to 20% in just five years (that's 46 million!), and there are constituencies that are going to be taken over by majority nonreligious people. The next step is getting more of those nones to equate "none" to "atheist" and openly identifying as such.
I recommend this article inspired by the recent news, and looking at the American secular movement in its historical context. In particular he points out how modern, organized secularism in the U.S. is at least in part a reaction to politically ascendant Christianity in the last 25 years. While this may be its roots, I don't know about you, but I aspire to make rationalism more of a positive worldview than a reaction to someone else!