(Joe McDonald, AP) BEIJING - Apple's iPhone is making its long-awaited formal debut in the world's most populous mobile phone market, without a key feature and at higher prices than widely available black market models. Apple's local service provider, China Unicom Ltd., hopes the iPhone will give it an edge against giant rival China Mobile Ltd., the world's biggest phone company by subscribers. Unicom was to start selling iPhones equipped for third-generation service Friday night at 2,000 stores in areas as farflung as Tibet.