Photos of the Week: Katy Perry, Vampire Weekend, Adam Lambert, Ke$ha
Katy Perry flashed the rock given to her by Russell Brand. Simon Cowell quit "American Idol" and announced the launch of "X-Factor" U.S. Vampire Weekend rocked London, Christina Aguilera hopped on a motorcycle, and Adam Lambert and Ke$ha hit the town hard. It all happened this week, and we've got the pics to prove it.
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