I saw an actual musical saw this summer at the Lunenburg Folk Harbour Festival. Apparently the saws played musically are different, possibly in the type of metal used. I don't remember if they have teeth like a regular saw or not, but they, like fiddles, etc, can use rosin.

One interesting thing the lady was saying is that the bend point and curve is what determines the note that is played. Which upon thinking about it, makes perfect sense.

Anyway, it certainly was an interesting discussion.