Stand Up to Cancer: Taylor Swift's New Song, Robert Pattinson and More Big Moments

Second star-studded telethon, also featuring Jessica Biel, Justin Timberlake, Gwyneth Paltrow, Halle Berry and Coldplay, takes over major broadcast networks

Taylor Swift didn't need a breakup song to break hearts tonight.

The 22-year-old debuted her new song, "Ronan," at the third Stand Up to Cancer event, televised Friday on cable and all four major broadcast networks, and there couldn't have been a dry eye in the house when she was finished. Swift shares songwriting credit on the single with Maya Thompson, whose 3-year-old son Ronan died of neuroblastoma last year.

All proceeds from the song, which is now available on iTunes, will go to cancer research. And Swift's simple acoustic performance was just one of many highlights from the reliably star-studded event, which this year was also a tribute to late film and TV producer Laura Ziskin, who lost her battle with breast cancer in June 2011.

Here were some of the night's most memorable moments:

• Testimonials from the kids: Little ones like Justin Miller, diagnosed with neuroblastoma when he was 3, were the real stars of the show, daring us to both smile and weep at the same time. "I don't really think about me passing away. But if I do, I'm taking my Legos with me," said Justin, who, unlike some of the other children profiled tonight, was well enough to be in the audience. Justin Timberlake did the shout-out honors.

• Another Robert Pattinson sighting: A night after introducing the newest Breaking Dawn Part 2 trailer at the MTV Video Music Awards, the Brit followed Jeremy Renner, who talked about a new form of gene therapy called the priming effect that's being used to fight cancer. "See, this is what happens when you support this movement," Pattinson said. "Every cent goes to the kind of research that is finding real breakthroughs and changing the lives of patients and their families right now."

• Mellow but exhilarating performances: In addition to Swift's fine showing,  Alicia Keys, looking stunning with that new slicked-back, short 'do of hers, sang "Not Even the King," Coldplay trotted out their mega-hit "Paradise" and Tim McGraw closed the show with "Live Like You Were Dying."

• Katie Couric razzing Chelsea Handler: Couric, who lost husband Jay Monahan to colon cancer in 1998 and has become a major advocate for preventative screening and colon health, tossed in a little joke while touting the value of a cleanse regimen. "Before you get your butt to the doctor, it's bottoms-up for a big gulp of the mother of all cleanses," she said via pretaped video. "It comes in vanilla, strawberry...I think Chelsea Handler even has one that's vodka-flavored. It is not the tastiest beverage in the world, but it is a small price to pay for potentially saving your own life."

• Celebs answering phones!: Handler worked the lines, Eric Stonestreet humbly calmed down an excited fan, and fellow famous types like Joe Manganiello and Kobe Bryant were on hand to make dozens of donors' days.

• Stars out in force: Along with Renner, R.Pattz, Couric, Timberlake and the musical guests, Halle Berry, Tom Hanks, Gwyneth Paltrow, Jessica Biel, Samuel L. Jackson, Julia Roberts, Michael Douglas and Sofia Vergara gave live testimonials, while Matt Damon and major leaguers baseball stars like Derek Jeter and David Wright starred in pretaped messages.