When Atlanta’s Andre 3000 and Big Boi galvanized their down-South fan base years back by releasing solo albums combined as an OutKast double album, many thought it was the last we’d seen of the playalistic duo as a united front. Now it seems that assumption was both true and misleading. Idlewild, the soundtrack for OutKast’s Prohibition-era musical movie, is made up of both members’ separate identities. They share only a handful of tracks, including the exceptionally rousing ‘PJ & Roosterâ?� and the more traditionally rapified ‘A Bad Note.â?� But the spirit that’s infected Andre in his later career ‘ a fedora-donning Casanova on Love Below, resident-in-chief of a sleazy speakeasy on this recording ‘ finally crosses over into Big Boi’s Cadillac-chrome world. The experimental songs on Idlewild showcase Boi’s inspired second wind. ‘The Trainâ?� is a poignant look back at an eventful career, and ‘In Your Dreams,â?� with its yearning chorus and broody piano clinks, surrounds Boi and Killer Mike’s melancholy posturing with the honey-dripped talents of Janelle Monae, outdoing Boi’s counterparts’ best efforts at nostalgic fusion.