Which is two months after he declared for the presidency.

Archive.org shows that the Dystel website used the following biography for Obama as of April 3, 2007:

BARACK OBAMA is the junior Democratic senator from Illinois and was the dynamic keynote speaker at the 2004 Democratic National Convention. He was also the first African-American president of the Harvard Law Review. He was born in Kenya to an American anthropologist and a Kenyan finance minister and was raised in Indonesia, Hawaii, and Chicago. His first book, DREAMS FROM MY FATHER: A STORY OF RACE AND INHERITANCE, has been a long time New York Times bestseller.

Obama launched his presidential campaign in February 2007.

By April 21, 2007, the Obama bio had been changed to state that Obama was born in Hawaii:

BARACK OBAMA is the junior Democratic senator from Illinois and was the dynamic keynote speaker at the 2004 Democratic National Convention. He was also the first African-American president of the Harvard Law Review. He was born in Hawaii to an American anthropologist and a Kenyan finance minister and was raised in Indonesia, Hawaii, and Chicago. His first book, DREAMS FROM MY FATHER: A STORY OF RACE AND INHERITANCE, has been a long time New York Times bestseller.

Interesting, no? Obama had been elected to the US Senate in 2004.

Watch the Washington Post and the rest of the mainstream media treat this story as not very interesting at all.