I spotted this the other day in my contacts' photostream on flickr and have been obsessing over it ever since. This afternoon the girls and I made a batch, and they had a blast. We started with white cake mix and split it into different bowls to dye with neon food coloring. Then I put the colors into separate pastry bags to make it easy for the girls to fill up the cupcake liners.
They were so proud of their cupcakes, they didn't even want to put frosting on them...at first. We'll finish up the ones they haven't already scarfed down after supper. :)