in 2004 the black vote represented 13% of the total populations vote. As a percentage of the total in 2008 it looks to only be 1% or more than 2004.
So whether it was racism or ignorance it didn't have a greater impact then any other election year.
BTW..Im selling my business before Obama raises the Capital Gains tax. I'm going to become a community organizer. Interested in joining me?