There was a rather pointed discussion on one of the Usenet folk groups on what this instrument should be called. The Jew's Harp people seem to have had the upper hand but there was some bitterness. You might do a Usenet search on Dejanews and read the debate.
I have often heard it used by French Canadians at their parties. There was a time when people used to play music on the trains here to pass the time, especially on the eastern runs, and someone always seemed to produce one of these things. I haven't been on one of the long-haul trains for years so I don't know if these impromtu jams still go on.