Indeed, Obama is really not from anywhere in particular, but he has strong roots in Kansas, Hawaii, California, New York City, Boston, Chicago (and Springfield), and Washington, D.C. He has relatives all over the world. Such geographic diffuseness, shared too by John McCain and Hillary Clinton, Obama's two main rivals for the presidency, can only lead to a bigger sense of the relationship between geography and identity, a definitive plus when being a politician.
It also helps being a person. This country is big and while it contains a core culture, the differences between us can also be significant, enhanced by tone and dialect and masked by common language. At the same time, we're a mobile society, and so where we're from is sometimes a difficult determination. I think that's why McCain, Clinton, and Obama have never really suffered being outsiders in the states from which they made their big political leaps.