Pearl Jam singer Eddie Vedder will appear on "The Late Show With David Letterman" July 28 to perform with avowed hero and former Who guitarist Pete Townshend, according to the show's booker. The appearance will promote an upcoming concert headlined by Townshend to benefit Chicago's Maryville Academy, a treatment center for abused and neglected children. Vedder has been paying homage to the Who over the past month. On Wednesday (July 14), wearing a blond wig, he was joined by Olympia, Wash.'s C Average for a surprise set of Who classics at the 510 Columbia club in Olympia. They performed in Who drag and fake English accents, ending with an instrument-smashing finale. Vedder also performed June 26 with C Average at the La Paloma Theatre in Encinitas, Calif., where they performed a cover of the Who's "Tattoo."