First introduced in 1999 as the "Eggparka", Mugen Denko's "Hit Air" motorcycle jacket comes with built-in airbags. Here's a picture of the inflatable cushioning sytem:
In the event of an accident and a rider is thrown from the motorcycle, the air cushion instantly inflates (within 1/2 second) to protect the rider's body. Activation is simple and automatic. A coiled wire is attached to both the motorcycle and the jacket. Once the rider and the motorcycle are separated, the coiled wire pulls a "key" out of a gas release system and inert gas inflates the air cushion. The inflated jacket provides the necessary impact protection.You can see some videos of it inflating here. It doesn't look like it would provide complete protecion in a crash, but every little bit helps.