I don't think Obama should outright "reject and denounce" Rev. Wright. Pulling a Sister Souljah on him would (1) seem like a sign of weakness (run away! run away!) and (2) be divisive (since a lot of people agree with what Wright said). I think political campaigns today spend to much time running away from a controversy instead of embracing it as an opportunity to make a statement that elevate our politics.
Obama needs to use his "crazy uncle" talking point as the kernel of a speech that hits on (1) the fact that we all have people in our lives that we love and cherish but who also do and say things that we disagree with and are sometimes disgusted by, (2) that many people agree with Wright and that national unity means we simply can't reject those people because they have ideas that we find disturbing, and (3) that the greatest thing about America is its ability to absorb the positive things from people, even if we reject some of their ideas.
This speech would hit on the importance of family, community and the nation and how all three survive and thrive because of the diversity of opinions within them, not despite them.
That's the kind of emotional appeal I would like to see coming from Obama (or any other leader for that matter).