We've actually seen this megaphone idea implemented before. While it's probably easiest to just go ahead and plug your iPhone in rather than trying to mechanically amplify the sound waves with a series of cones and chambers, that hasn't stopped some designers from putting together some intriguing devices for making your iPhone louder (and clearer?).
All that said, we'd like to say this "acoustic horn" manufactured out of ceramic and placed on a walnut tripod was just another jokey accessory, but given how well-designed it looks? We'll just say: No comment.