A guy in my lab played has been playing with something like this off and on for a while, for a different application. My understanding of the technology is that it requires fairly high voltage but extremely low current to work, so the power draw is rather low.

A bigger concern is what happens when you get it wet. This changes the conductive properties of the skin, so you go from a barely noticeable 'tingle' or 'friction' effect to a noticeable shock (think static shock). Thankfully, the current is too low to be dangerous in most cases, but defective circuits could still be a problem in production runs.

I'd be interested to see how this technology deals with such issues.