Hacking pacemakers to delivery deadly shocks remotely. The perils of adding too much technology without thinking through the consequences.
And there's plenty of other implantable devices this could work for. While I haven't fully researched it, I would guess that programable insulin pumps might be vulnerable (it would depend on how one connects to update the programing, and how the switch that delivers the insulin operates - the later in case you could just electronically brute force it). Then add in all the "future tech" (like Google Glasses - blue screen of death, yah, you betcha) coming on line.
Oh, and bluetooth added to devices also provides a gateway to this kind of attack, just saying.
This was pointed to by Dan. I was going to put it in a Linkee-poo, but that just screams "plot point" or even a Sherlock twist.