Green Day, Taylor Swift, Aerosmith, Rihanna, Mary J. Blige and other heavyweights will top Clear Channel’s 2012 IHeartRadio Music Festival, the centerpiece of the company’s expanding live performance biz.The lineup for the event, which unspools Sept. 21-22 at the MGM Grand in Las Vegas, also includes Usher, Bon Jovi, Lil Wayne, Swedish House Mafia, No Doubt, Brad Paisley, Pitbull, deadmau5, Miranda Lambert, Enrique Iglesias, Linkin Park, Jason Aldean, Pink, Calvin Harris and Shakira. The success of last year’s inaugural concert launched iHeartRadio, Clear Channel’s free digital music service, Clear Channel, the nation’s largest radio broadcaster, has been forging an innovative path for broadcast and digital radio and dipping its toes into other media, Company bills IHeart, hosted by partner Ryan Seacrest, “the biggest live concert festival in radio history.” IHeartRadio hit 10 million registered users in May with access to more than 1,000 live broadcast and digital stations from 150 cities as well as the ability for users to create custom stations. Earlier this year, Clear Channel acquired a minority stake in Ryan Seacrest Productions. And Clear Channel owners Thomas H. Lee Partners and Bain Capital committed up to $300 million to develop entertainment projects with him. Last month, Clear Channel unveiled a groundbreaking deal with Big Machine label to pay its artists royalties — taken from advertising revenue — for terrestrial broadcasts.