In his post on affirmative action today, Adam writes, "No one has to know that a white person applying for a job grew up in a trailer park or project housing, so class based discrimination is practically irrelevant."
I disagree. Classism can be quite ugly, even in the absence of race or gender-based discrimination. A person's class identity is often revealed by their accent, the particular high school or college they graduated from, and their ability to make appropriate cultural references. The most basic rules of how to apply for college or a job and behave in an interview are also more accessible to people from higher classes -- after all, class is a marker for educational attainment, as well. So there are lots of reasons to support class-based affirmative action other than that it will also do a good job of helping address racial discrimination.