@Anony Mous - I agree with you that America hasn't had a black president yet.
But 'Obama is black'? The dude's half white. If I claimed him as a white president, you'd think I'd gone nuts, but this is little different from claiming him as black.
Personally, I'd rather we concentrate on a person's character and, for a politician, policies.
But if we're gonna talk about race, let's try and be accurate, y'know.
Over in the UK, we'd call Obama mixed-race. I'm not sure if this is derogatory to Americans - I think you guys prefer the term 'biracial'.
Barack Obama - first biracial US President. <--- nothing wrong with this.
PS - just noticed you've edited your comment 'Obama was black' to 'Obama was perhaps black (at least 50%)'.