Sarah Palin has accepted David Letterman's apology for the joke he made about her daughter. In a statement yesterday, the Alaska governor said the apology was accepted “on behalf of all young women, like my daughters, who hope men who ‘joke’ about public displays of sexual exploitation of girls will soon evolve.’’ On his CBS “Late Show’’ Monday night, Letterman said his joke about one of Palin’s daughters being “knocked up’’ by Alex Rodriguez can't be defended. He said the joke referred to 18-year-old Bristol Palin, not her 14-year-old sister, Willow. But Letterman said it's his responsibility that people believed that he intended to target Willow, who had attended a Yankees game with her mother.