The article
The man in the picture to the right may be the only man to my knowledge that can play the drums with three drum sticks. Jason Barnes, the man you see in the picture, lost his right arm below the elbow two years ago.To keep drumming, he built his own prosthetic, but it didn't provide him with the same level of control as a wrist and fingers would have. Weinberg was able to develop a more advanced prosthetic that is controlled physically by the Jasons' arm, as well as electronically using electromyography (EMG) muscle sensors in his upper arm, allowing him to adjust the prosthetic's grip on the stick to control how much it rebounds. Already this is a pretty cool prosthetic. Then Weinberg took it a bit further and gave the prosthetic arm a second stick. And a brain to control it. That second stick literally has a mind of its own: it listens to the music that Jason is playing, and then improvises an accompaniment to play along with him. Jason can't control the second stick directly, but he can pull it away from the drum when he wants to play on his own. What's fascinating, though, is that the second stick allows Jason to do stuff that humans can't do. He can play faster, with a more stable beat, than any human can, because he's part robot. Eventually, Weinberg wants to integrate this arm directly into Jason's brain so that it'll be able to predict when he wants to hit the drum, and then make sure that it activates to nail the beat at that exact moment.
The implications
Beyond the more obvious implications of improvements and advances in the prosthesis field in terms of better limbs for those that have lost them; the bit I find to be the most promising is Weinberg's interest in integrating Jason's arm into his brain to improve its overall function. This could lead to use of such robotic synchronization technology that could potentially be used in the future by fully abled humans to control an embedded, mechanical third arm during time-sensitive operations like a surgeon or astronaut.