Washington Post columnist Eugene Robinson took home a Pulitzer Prize in Commentary today, “for his eloquent columns on the 2008 presidential campaign that focus on the election of the first African-American president, showcasing graceful writing and grasp of the larger historic picture.” It’s the only Pulitzer the newspaper got this year, marking a step back from last year, when the paper took home a record six awards. In 2007, the paper got none, in 2006,…