There is a meme on the Left that the Right is using racial "dog whistles," that is, codes that are detectable by racists but aren't heard by the rest of the populace. The evidence for this is thin as far as I can tell.
What is much clearer as the link above makes out is that the Democrats and Obama are attempting to create an "Invisible Fence" around him using race to shield him from the normal inquiries a candidate must face. Criticize a 20 year relationship with a Reverend Wright-your a racist. Criticize his weakness on crime? Closet racism. Wonder about his attachment to patriotism-patent racism. Disagree with him on "affirmative action"-racist. Clain he is ignorant of foreign affairs-racist.
To criticize Obama is to be racist goes the meme. The Democrats are using the race card to keep Republicans away from weaknesses possessed by their candidate that would be fully exploited if his father had been as pale as his mother.
The Left has never apologized for the ad that ran against George Bush implying he was a racist who wanted to drag African-Americans behind pick-up trucks, when in actuality he was for the death penalty for such acts. John McCain and the Republicans had better be ready to brush this nonsense aside because Obama is increasingly vulnerable on matters of trust and truthfulness (see campaign finance reform) and they cannot afford to pull punches because of false claims of racism.