Here are my slides:
During one of the Maker Fairs, I sketched this out to help illustrate the various functions the micro-controller does on the layout:
All together, it is a bit overwhelming, even for me, but taken a piece a time, it is quite doable. Instead of bringing the full layout, I used the Sparkfun Inventor Kit and a small section of track to demonstrate the various ways I use Arduino.
I think it went well. I got lots of question during and after the seminar. It was obvious they were thinking about ways to apply this to their own layouts!