Glenn,
I think it is a very worthy thing to try - I am certainly trying it this summer, as we finally got enough wood chips to do these experiments!
So far the coffee/wood chips piles look very promising. They heat up almost instantly (the next day), and stay hot for a long time. They smell great too
I have a wood chips pile that is kept moist, but does not have coffee grinds in it, and it stays cool. So it is not breaking down on its own. Needs nitrogen!
Coffee grinds and wood chips are free resources that we could utilize more.