The Zune team has posted a flash animation which will help you understand how the new touch-control available on Zune 4, 8 & 80 works before you buy one of these. It has two modes: normal 5-way click mode, like the one on Zune 30, and touch mode where you can nice and easy scroll up-down and left-right slowly or move your finger fast and it will keep scrolling until the control is pressed again...
Link:
The Zune Pad Demo