We have had similar ones in sushi shops for years in Japan: http://www.garbagenews.net/archives/1511123.html

And some of them can be used with Nintendo DS: http://www.garbagenews.net/archives/1406127.html

As far as I observed, one of the problems with these devices is they give the restaurant a bit of cheap look. That's partly due to their poor make, but most probably, the guests feel embarrassed similarly to when one takes out his cell phone just in the middle of dinner.