No surprise: he's for it. And just to be clear, when Obama defends affirmative action, he is defending, specifically, decisions that rely on race as the decisive factor, what some call "racial preferences":
The [Harvard Law Review] Selection Committee first identifies the group of candidates whose excellent performance, either in the classroom or on the writing competition, sets them apart.... The Selection Committee must then choose the remaining editors from a pool of qualified candidates whose grades or writing competition scores do not significantly [whatever that means-ed.] differ. It is at this stage that the Law Review as for several years instituted an affirmative action policy for historically underrepresented groups: out of this pool, the Selection Committee may take race or physical handicap into account in making their final decision.
Again, no surprise, given that it's been reported that at rally for faculty "diversity," Obama compared Prof. Derrick Bell, who was pressing the law school to immediately hire an African-American woman, to Rosa Parks (because being subjected to brutal racism in Alabama in the 1950s is just like being a tenured Harvard Law School professor in 1990?). Still, interesting to see Obama's own words.
Obama also notes that he was likely a beneficiary of affirmative action preferences during his academic career. I know some Obama-haters are inclined to use this against him, but, in fact, given his successes ever since, Obama would more likely be the poster child in favor of affirmative action.