I don't have much directly to say, just some links. I had a discussion with Paul Hewitt on biased hiring at Overcoming Bias which migrated to a top-level post at my own blog. It was not an ideal conversation since I was trying to find whether there was any data on gendered productivity differences and he was trying to exposit the logic of a model in which employers fail to learn.

Karl Smith replied to Bryan Caplan on stereotypes by analogizing it to pollution here.