Taylor Swift has been pretty busy promoting her new album, 'Red,' but country music's sweetheart is never too tied up to make a kind gesture. Tonight at the third annual 'Stand Up to Cancer' telethon, Swift is going to devote a new song to a 4-year-old boy named Ronan, who died last year of neuroblastoma. The song, aptly called 'Ronan,' is a co-write with the boy's mother and has never been performed publicly.

Swift will rock the SU2C telethon audience with a sure-to-be unforgettable performance of the new tune. Immediately after she takes the stage, the song will be for sale on iTunes. In true Taylor Swift fashion, the proceeds won't go into the country singer's pocketbook -- they'll go straight to cancer-related charities.

Swift wrote 'Ronan' after reading the heart-wrenching blog entry of the boy's mother, Maya Thompson, who later helped the 'We Are Never Ever Getting Back Together' singer pen the tune for her late son. According to the Sacramento Bee, a person who is familiar with the event (but stayed anonymous because he or she was not authorized to speak), this will be Swift's first time to perform the tune in front of an audience.

Both Swift and Tim McGraw will be on hand at the event to represent country music. Tom Hanks, Halle Berry, Justin Timberlake, Ray Romano, Olympic Gold Medalists Gabrielle Douglas and Missy Franklin and a handful of other celebs will also make appearances.

SU2C will air on tonight from 8 to 9PM ET. Major networks like ABC, CBS, FOX and NBC will donate one hour of simultaneous commercial-free prime-time programming for this nationally-televised fundraising special. The event will be broadcast live from the Shrine Auditorium in Los Angeles.