Oprah's campaigning for Obama is very important and will have a huge impact on the race. She gives women permission to vote for Obama rather than for Hillary. She tells blacks that it is important to vote for Obama. And she puts distance between Obama and Edwards, the pesky third-place challenger whose lingering strength in Iowa threatens to muddy the Obama victory over Hillary.

Normally, celebrity endorsements mean little. But as America's best-known and best-liked woman and black, her endorsement means a great deal in an election based on the convergence of the first woman and the first African-American to run for president.