I'll answer that.
First, he has no experience that is a stumbling block. Hillary has a lot of baggage. John Edwards is boring and just doesn't connect. No other candidate is connecting with people in a real meaningful way. Obama is offering people something no other candidate - Republican or Democrat - is offering. He's offering them an emotional "feel good" message of hope, hence the title of his book "The Audacity of Hope." He is trying to ride the wave of John F. Kennedy, camelot is beautiful type of campaign. The color of his skin is not really an obstacle because the only people who would not vote for him on account of his being black wouldn't vote for a Democrat anyway. Some of the people who would vote for him because he is black wouldn't vote for him if he were a Republican.
None of this is to say I will vote for him or support him. I'm also not saying Oprah isn't a racist, but don't think she's supporting Obama on the basis of race alone. I think Oprah is supporting him because of his message. She didn't endorse Alan Keyes and she didn't endorse fat ass Al Sharpton either. She likes Obama's feel good message.