Despite my protestation in the previous post, Ayers also does not matter. It WAS a long time ago. Barack Obama was a kid when Bill Ayers was off on his bomb throwing. The median age in the United States is about 36 so most Americans were not even born during the events of 1968 while others (such as myself) have no memory of those events (I was 1). And it was such a horrible time in America, I would imagine that most of those around at the time have suppressed much of the memory.
But for those not on a college campus or on a battlefield in Vietnam, was it such a horrible time? My parents always looked back wistfully at their childhood, even though they were born during the Depression. I used to jokingly ask my parents how they survived the 60s, and you get the feeling that they were too busy dealing with their own issues, jobs, saving for a house, going through the difficulties of trying to have a baby (my Mom had problems on that front) and finally raising me -- they did not have time to worry about bomb throwing radicals and the campus ideological battles between the SDS and YAF.
Given the challenges faced by the next president regarding the subprime meltdown and the continuing war in the Middle East, refighting 1968 is probably low on everyone's list of things to do.