A coming paper by a University of Pennsylvania professor and a Cornell University graduate student says that, during the 13 seasons from 1991 through 2004, white referees called fouls at a greater rate against black players than against white players.Except that it really doesn't say that at all. This isn't a bullshit study by any means. I've read that the authors do a great job of considering a multitude of potential confounders, and that the authors do mention alternative hypotheses that their data cannot distinguish between, and that's heartening.
But the paper (or at least those interpreting it in the media and blogosphere) seems to be making a fundamental ecological error of attributing community level behavior to individuals. The study suggests that having more white refs on a three-man referee team leads to more fouls on black players, but it has no means by which to imply that white referees call more fouls on black players.
While not as elegant an explanation, a black referee with two white referees in his group might be more likely to call a foul on a black player, and the white referees might make no distinction.
The proper conclusion of the study is that a community-level effect exists, and another study needs to be performed addressing which of the individuals makes the call to create strong evidence for any individual level bias hypothesis. As the NBA has that data and will not release it, and no grad student probably has the time to watch 1500 basketball games a year to generate the data, I doubt we're going to get an answer.