The main argument deployed by opponents of Sonia Sotomayor's appointment to the Supreme Court seems to be that she was chosen because of her ethnicity and gender. This argument is pretty weak even if true, which it is largely not.
Obama certainly considered the gender of his nominees; all of the rumored possibilities were women. Obviously, since they all had distinguished legal and judicial careers, their gender was not the only factor. In fact, they were all apparently qualified for the nomination. So where does this leave the "affirmative action" argument? It's left holding the assumption that a white male candidate or candidates would be more qualified. Obviously, anyone making this type of argument is bigoted, since the "most qualified" candidate could be a transgendered Trinidadian, as opposed to a white male. And if Obama nominated the transgendered Trinidadian, Bill Buckley and his ilk would be making the EXACT SAME ARGUMENT. The only way to quell Republican wailing about the poor, beleaguered, oppressed white men would be to nominate only white men.
Then you get to the actual absurdity of the phrase "most qualified". When you're considering someone as a Supreme Court nominee, there is no dial stuck in their abdomen that reads out a single "Qualification Index" metric. "Qualified" is a necessarily vague and subjective evaluation. Which raises the "qualified" metric more: two years as a Federal judge or five years as a District Attorney? You are evaluating the whole fruit basket, so you make judgment calls about the relative values of apples and oranges. Is Alito "more qualified" than Sotomayor or is this just a facile comparison. And if you came up with an answer, was it based on concrete evaluation of experience or was it influenced by your prejudices?
So even if Obama did consider gender and/or ethnicity in his selections, there's nothing wrong with that. Diversity of background adds value to the Supreme Court (which, I believe, was a theory advanced by Alito at his confirmation hearing). Those who cry "Politcal Correctness has run rampant!" should carefully consider the definition of politically correct. I think the 'politically correct' choice would be to choose an old white man again, as is apparently traditional.
Anybody who's not full of shit will say that gender was a factor in Obama's selection, but far from the sole factor. Nominating a female was probably a far less significant factor in Obama's decision than nominating males was in Bush's decisions. Republicans want us to think that their selection process is gender- and race-neutral; and it's just a coincidence that they go for a white man 99.5% of the time. Objectively most qualified, don'tcha know!