Blissed Out: Star Weddings of the Year

Justin & Jessica! Drew & Will! See the famous couples who flocked to the altar in 2012

MARK & PRISCILLA

Friends and family of Zuckerberg, 28, and Chan, 27, thought they were invited to the couple's Palo Alto, Calif., home to toast Chan's graduation from medical school – but instead were treated to a surprise wedding on May 19. Escorted by their dog Beast, Chan wore a dress by Claire Pettibone and was serenaded by Green Day's Billie Joe Armstrong. "They genuinely love and respect one another," the Facebook CEO's sister Randi said.