When you run into someone you know at WDW, you do realize what a small world it really is (pun intended).
This past January, I ran into a co-worker at AK, near Y&Y. She was nearing the end of her trip, and I was at the beginning of mine. My department at work consists of 250 people, so not small, and neither of us knew that the other had a serious disney addiction. It was cool to find that out in the middle of a theme park!
A few years ago, at a restroom in Epcot, I ran into a woman from church/school, and her kids. At the time, our children attended a small Lutheran school in my town.
It is kind of wild to run into people you know at WDW!