Talking While Black
Steven Levitt writes up some new research on race, speech patterns, and earnings done by Jeffrey Grogger:
His main finding: blacks who “sound black” earn salaries that are 10 percent lower than blacks who do not “sound black,” even after controlling for measures of intelligence, experience in the work force, and other factors that influence how much people earn. (For what it is worth, whites who “sound black” earn 6 percent lower than other whites.)
Follow at the link for an explanation of how who "sounds black" was determined. Whites with strong southern accents appear to suffer from a similar problem, though I think that since the experiment wasn't really designed to measure that the estimate is very imprecise.