I'd buy one, but I'd not use it when I bike, though. At least not for music and definitely not in traffic! Geez, that's worse than talking on the phone while driving because a rider is almost invisible to most drivers anyhow, especially in places that might not be so bike friendly and accessible, and they need to use their ears as much as their eyes. IMHO, of course.
RE: Google and Levi's Create A New Wearable: A Smart Jacket That Connects To Your Phone!