"pins & needles"?

[Baker, John]

        I've heard both meanings of "pins & needles," with the metaphorical usage more common.  There is often a suggestion of anticipation as well as anxiety:  "I was on pins and needles waiting for the test scores."  "On tenterhooks" is far less common in my experience (having lived in Kentucky, Massachusetts, and now Maryland in the sniper area), and it strikes me that I do not know what a tenterhook is.

John Baker