I implemented vApplicationIdleHook just like in the ebook.  Every second, I have a task which prints out the value of ulIdleCycleCount.  the value hovers around 2,724,536.   Sounds like a nice beg number which, I think, means we have lots of idle time, but I am not really sure.  What does that number really mean when I am running a PIC32 at 80MHZ?  thanks!

Is ulIdleCycleCount a variable that just gets incremented each time vApplicationIdleHook() is executed? If so, then all it is is a count of how many times the function has been called.

Is there a way to correlate that to % of CPU used? 
thanks!

No. If you want to know the % of CPU used then you can do one of three things. 1) Use run time stats http://www.freertos.org/rtos-run-time-stats.html 2) Use the traceTASK_SWITCHED_IN trace macro to see when the idle task is switched in, and when it is switched out, and use a timer to keep track of when it is the task in the running state. 3) Use the idle hook to toggle a digital output pin and view it on a scope. Crude but effective. Probably other things too.