The Annual Costume Institute Gala

John Mayer and Jessica Simpson

A collective buzz greeted John Mayer as he made his entrance, but the woman on his arm wasn't Jessica Simpson—who arrived much later and in the company of another man. While Mayer squired Roberta Armani down the carpet, his pop princess posed with Roberto Cavalli in one of the designer’s own disco-esque creations.

Next: Sandra Bullock

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