We can't say for sure, but there must be a lot of cars hitting a lot of walking people in Japan, because they have a very, very "healthy" fascination with keeping cars from hitting them. Or, in this case, if they are going to hit them, they might as well hit them without much damage to their face (or rest of their body). Though, depending on how fast the car is going, we're not sure airbags on the outside of the frame will do much to save anyone.
The exterior air bags are actually specially crafted car body panels, and they are the design project from many researchers, and was the idea of several companies based out of Hiroshima, as well as the local university. iSAVE is designed to rapidly deflate the airbags upon collision, just like the airbags you have in your car right now. There's only one car in the world right now equipped with iSAVE, and it's just a prototype right now. And, while it may be a good idea enough to put it on every car out there, it seems that the researchers are claiming it only works with electric cars.
The researchers plan on having iSAVE fully commercialized by 2011. Until then, though, they plan to sell upwards of 50 units for 3-wheeled vehicles. Pricing on four-wheeled cars was revealed though: $17,800. So, it's not a cheap option, but if you know that you aren't all that safe about staying in your lane (or not on a sidewalk), maybe you should think about getting yourself a new (electric) car next year. Obviously, sound isn't good enough to keep those pedestrians safe.