Indie rockers Band of Horses and electro-pop outfit Gotye will perform as part of the ongoing Live on Letterman concert webcast series later this month. Hours Before the Release of their new album, Mirage Rock, Band of Horses will perform their Live on Letterman set on September 17 at the iconic Ed Sullivan Theater, while Gotye will perform songs from his recent album, Making Mirrors, on September 24. Both performances will be webcast live on CBS.com and VEVO.