Racist sociolinguistics from El Rushbo?

Politicians’ slips of the tongue hit the news from time to time, with observers often trying to read more into them than is really there.  But Hendrik Hertzberg (“Decoding Limbaugh“, The New Yorker, 2/23/2010) argues that Rush Limbaugh has recently reached a new low in mean-spirited misinterpretation. [Update: more here.]