I teach multivariable calculus, AP Physics C, and precalculus at a US private school and use LaTeX extensively, though I learned LaTeX pursuing degrees in math and physics. I primarily use LaTeX to create custom homework assignments, which students seem to enjoy more than their book problems. Recently,
pgfplots have made my life much easier.
The AP Calculus teacher at my school is a recent college graduate with a degree in math who never learned LaTeX, but knows of its existence. I am trying to convince him to learn LaTeX. My hope is that with good templates and me as a resource, he will learn some basic LaTeX. He has seemed extremely excited by
pgfplots, especially by the possibility for automatically drawn Riemann sums (Placing coloured rectangles on a plot, using points from the plot - Riemann Sums).
I doubt that any other teachers at my school would be interested in learning LaTeX (or would benefit from it). But I can imagine that as more young, math/physics/cs grads become teachers its use could spread.