I'm going to let Chris, who came up with the idea, explain the motivation:
Discussion of racism is often shot down by the nervous – conservatives and liberals alike - as "playing the race card," a close semantic kin to the "PC" gambit often used to squelch criticism of offensive language in the public sphere. Odd, then that objecting to the term is itself a form of political correctness: "don't say racist! That's offensive!" The thing is, if we discuss racism as a systemic ill, as a function of misinformation and reversible prejudice, if we describe racism in terms of effects rather than intent, then we do a couple things. First, we grant the possibility of redemption, the possibility that people raised in a racist society – me, you, everyone I know – can root out those prejudices. Second, we grant our opponents the freedom to think whatever they like: it's the effects that count.
Society needs to have this discussion. But the responsibility for discussing racism has long been relegated to those people most directly affected by it. In other words, people who aren't white. Us white folks have the luxury of not thinking about racism on a daily basis. As a result, most of us don't. I think it would be helpful if we started to do our share of that particular chore.
I'm going to take part but I'm not sure what I'll write yet. That's okay because neither is Chris, although some people have already jumped in. If you join the discussion, send a trackback to Chris here and he'll keep a running list of blogs participating.