As you can tell, the palm frond is glowing with dots, something like looks like it belongs in the Avatar movie. In this case, the dots are green, but it could be done with blue, I assume.
It was accomplished via refracted lights shining from underneath the leaf. The prism effect threw light dots all over the trees, the walkway, the people. It kind of looked like lasers, but I wonder if they weren't just LEDs since lasers strike me as dangerous to put onto people like that.
This example was found in the Christmas decorations at Lowry Park Zoo (in Tampa).
Kevin Yee is the author of numerous independent Disney books, including the popular Walt Disney World Earbook series and Walt Disney World Hidden History.