What affect will this have in the general election? Depends. Most of the news and chatter have given him a pass on the issue. Obama can talk about hope and change, but that promise has limits. You must be a certain age before his speech goals apply.
I hate to say it, but I doubt the knowledge will have much impact on the black vote: they seem settled to vote for Obama regardless of what he does or what he says which is really sad. However, in the general election, Obama's record could push many Hispanic and rural votes away from his candidancy. Right now Obama rides a black and upper crust wave. Primaries work with a relatively small lefty block. When he tries to hit the mainstream will he have swung too far to the left to ever return? If we want hope and change, let's hope that he has and move to change our America to a more welcoming place.