Feeling pain for getting shot in a video game?... It sounds like a horrible idea, but there could easily be some good things that come out of it. Like some people have mentioned above, it would make it so people would play a bit more strategically, so that they wouldn't have to expericence the pain, but still... pain? It would probably be more likely to be a simple shock, nothing more. Anything severe would cause me to not use it.
This idea will probably never actually come into video games though, because children play video games, and if they felt pain they'd end up crying, which equals bad reception against whoever created the technology.
I myself would rather work on a real-life simulation, where YOU are in the game, kind of like the holodeck in Star Trek (I'm a nerd). That would be freakin' awesome.