So much has been made of the fact that Obama is the first black nominated by a major party in a Western country that I feel it's overshadowing the true significance of his candidacy, which is something else and which I'll address above shortly. In any case, I think that was a milestone America was ready to pass almost a decade ago when Colin Powell could have gained the nomination from either party. What's more, Barack Obama is, properly speaking, mixed race.
That said, Ezra Klein HERE is good on the milestone, such as it is:
"Towards the end of the 1967 movie "Guess Who's Coming to Dinner," Dr. John Wane Prentice, played by Sydney Poitier, sits down with his fiance's white father, played by Spencer Tracy. "Have you given any thought to the problems your children will have?" Tracy asks. "Yes, and they'll have some...[But] Joey feels that all of our children will be President of the United States," replies Poitier. "How do you feel about that?" asks Tracy, looking skeptically at the black man in front of him. "I'd settle for Secretary of State," Poitier laughs.
"Written in the late-1960s, the exchange was, indeed, laughable. The Civil Rights Act had been passed three years prior. Two years before, the Watts riots had broken out, killing 35. Martin Luther King Jr. would be assassinated a year later. But here we are, almost exactly 40 years after theatergoers heard that exchange. The last two Secretaries of State were African-American and, as of tonight, the next president may well be a black man. John Prentice's children would probably still be in their late-30s. They could still grow up to be cabinet officials or even presidents, but they would not necessarily be trailblazers."
Hat tip Tigerhawk