(Capitol, Aug. 24)
When Katy Perry released her debut solo album, "One of the Boys," in June 2008, her musical peer group-cool big-sister types who titillate the training-bra set without threatening them-was in a dormant phase. Britney Spears and Christina Aguilera were in various states of repose, and good girls Jordin Sparks and Natasha Bedingfield minded their manners on the pop charts. Perry's "I Kissed a Girl," magnificently constructed by Max Martin and Dr. Luke, and persuasively delivered by this daughter of two evangelical pastors, shot to No. 1 on the Billboard Hot 100-the first of three top 10s from the album-and established Perry as a Cyndi Lauper of the sexting generation: a girl who chases after fun with near-religious fervor.