I was genuinely surprised that many people said that we live in a "post-racial America" after the 2008 elections. Including Chris Matthews, a news anchor, of all people said this!
Obama's election was indeed an historic moment, but it didn't magically erase prejudice and bigotry from this country. On the contrary, the political far-right channels all sorts of racist fears about the President to otherize him: "he's a foreigner, he's not Christian, he's got a Kenyan anti-colonial worldview, he wants to steal money from hard-working white folk!" It's sickening.
I've seen this "no racism in America" argument used by both the Left and Right under different contexts; barring intellectual dishonesty, I can't imagine how they got to this conclusion.