Here's an in-depth article about Wicked's design, there may be some detail about the show's lighting design in it.
http://entertainmentdesignmag.com/mag/show...ocus/index.html
Wicked is a terrific show, the scene I think you are referring to is "Defying Gravity" at the end of act one. It is an intelligent light fixture using a combination of a gobo, multi-colored gel, focus control and rotation. Most of the big Broadway shows are using the "High-End" brand of intelligent lights.