We used Racket for the introductory-programming component of the "Coalition for American Indians in Computing" (CAIC) 2010 summer camp, sponsored by Humboldt State University with funding support from the National Science Foundation.
The time allocated for this component was very limited: a total of four hours of class time and two hours of project-work time, spread across three of the camp days. It's amazing to me that, using Racket, even with so little time, the students were able to create nice compound image expressions, write a simple function (expecting a number and producing a scene) able to be animated using big-bang, and even get exposed to using branching to display one image in the scene or another based on the value of its parameter.