What does it mean to be Black in America?

Pundits are talking about Barack Obama not being Black. What does it mean to be black? As I think about this and read what other's have to say, it seems in the face of Obama, people are quickly readjusting their definitions. Being African-American is not enough, you have to be descended from West African slaves brought to the US. Are the pundits collectively redefining because Obama breaks the boundaries, including the assumed ones of class and power? For example, here is a quote from an article proclaiming that Obama is not black:

Not descended from West African slaves brought to America, he steps into the benefits of black progress (like Harvard Law School) without having borne any of the burden...
- Deborah Dickerson, Salon.com, Jan 22, 2007

Is Black really a class issue instead of a descent issue? Notice that Deborah Dickerson does not point out the reversal of Jim Crowe laws, which pertains to all African Americans, as evidence of black progress, but refers instead to Harvard Law School, which applies to a miniscule minority of Americans of any color. Although she does not say so explicitly, she's talking about Blackness as a Class issue. Yes, Class, which is something Americans don't like to talk about.

These questions come to me in vivid relief as I think about my brother and how he compares with Barack Obama. For those of you who don't know my family well, my brother, who sees himself as black, was adopted as an infant by my white parents.

Similarities between my brother and Obama:

• Bi-racial, half African descent, half European
• Raised by white family, at times overseas
• Both will be followed by security guards when they walk into a store
• Both will be pulled over more often than I will
  

The differences between my brother and Obama:

• Obama is white collar and has political power, my brother is blue collar and does not have political power
  

Other than the fact that pundits won't get on TV talking about my brother, on paper, my brother and Obama are alike in background except for their chosen career paths and subsequent rise in the socio-economic structure.

So, give me your thoughts - What is Black? Race? Ethnicity? Family history? Class? Some intersection of these?