The lineup for Z100’s 2011 Jingle Ball has been revealed!

Lady Gaga, Kelly Clarkson, Demi Lovato, and LMFAO will be hitting the stage at NYC’s Madison Square Garden on Friday, December 9.

Pitbull, Foster the People, Gym Class Heroes, David Guetta, and Hot Chelle Rae will also be performing.

Tickets for ZVIPs will go on sale Tuesday, November 1, at 4 p.m., before they’re available to the public on November 2 at 4 p.m. - you can also win tickets just by listening to Z100!

For more info on 2011 Jingle Ball, check out Z100.com!

Also pictured inside: Demi performing at Z100’s Jingle Ball 2011 official kick off party at Aeropostale Times Square.

30+ pictures inside of Demi hitting the stage at the big kick off event…

The iHeartRadio Music Festival lineup has been announced!

Ryan Seacrest will host the two-day music event, which will mark the biggest live concert festival in radio history.

Confirmed for the event, taking place Sept. 23 and 24 at the MGM Grand in Las Vegas: Lady Gaga, Coldplay, Alicia Keys, Steven Tyler, The Black Eyed Peas, Kenny Chesney, Jennifer Lopez, Carrie Underwood, Jane’s Addiction, Nicki Minaj, John Mayer, David Guetta, Rascal Flatts, Bruno Mars, Kelly Clarkson, Sublime with Rome and special performances from Usher and Sting!

For info on how to purchase tickets, check out iHeartRadio’s Facebook page. If you can’t attend, live audio and video streams will be available online, via mobile devices at www.iHeartRadio.com and across all of Clear Channel’s radio station websites.

Check out J. Lo making the announcement on the Today show!