Today’s celebrity rundown (13 photos)

Katy Perry got a short new ‘do. She showed up with her husband Russell Brand to the 3rd annual ‘Change Begins Within’ benefit celebration in Los Angeles on Saturday.

JoJo celebrates Christmas with butt flaps.

Hitting up the big apple, Taylor Swift arrived at the Billboard Women in Music luncheon where she was honored as Billboard’s Woman of the Year.

This morning on NBC’s ‘Today’ show, Giuliana Rancic announced that she will undergo a double mastectomy after her lumpectomies failed to completely eradicate her breast cancer. Husband Bill Rancic was by her side during her public announcement.

“At the end, to be honest, all it came down to was just choosing to live, and not looking over my shoulder for the rest of my life,” Rancic said.

Angelina Jolie is on the cover of Newsweek.

Jolie‘s approach to her humanitarian work: “When I go somewhere, I am always willing to learn about it. I get briefings, I read books, I talk to people,” she said. “But mainly I try to go somewhere to bring awareness, to come home and pick up the phone and call someone and try to get something done.

She brings the same approach to filmmaking: When it comes to the technicalities of making a film, “I wasn’t afraid to ask the DP [director of photography]. And I listened to my cast, most of whom lived through the war. I listened to their stories and tried to incorporate it into the work.”

‘Breaking Dawn’ spends the third week in a row beating out ‘The Muppets’ and ‘Hugo.’ The Box Office stats show that ‘Breaking Dawn’ pulled in $17 million during its third weekend of release. ‘The Muppets’ trailed behind with $11 million, ‘Hugo’ with $7.5 million and ‘Arthur Christmas’ only had $7.3 million.

Stars came out to support The Trevor Live event at the Hollywood Palladium yesterday. Fergie, Josh Duhamel, Dianna Agron, LeAnn Rimes, Christina Hendricks, Zoe Saldana and Amy Poehler were a handful out of the many celebs who showed up.

Lady Gaga performed at KIIS FM’s Jingle Ball in LA. That’s one hell of a motorcycle/rocket/prop thingy she has going on behind her.

New York Times had Viggo Mortensen as this weekend’s cover boy. During his interview he got straight to the point and said, ‘Life is too short to work with idiots who are rude and selfish.’

And the Super Bowl XLVI halftime performer is… Madonna. The material girl will take center stage on February 5, 2012 at the Lucas Oil Stadium in Indianapolis.