"Has there ever been a better moment for tween girls?" asked Ada Calhoun in the L.A. Times last week, pointing to the cultural ascendancy of Disney and Nickelodeon robots Hannah Montana, Taylor Swift, iCarly and Selena Gomez. Then fans of American Idol watched as an army of twexters voted for dreamy over Didi. ("America is a teenage girl," lamented TV blogger Richard Lawson.) So strong is the spirit of this young generation that even the women of my own just-older cohort have sought its approval, offering up recycled heirlooms from our own childhoods like so many olive branches. Just hitting bookstores is The Summer Before, [...]