Talk about a color makeover! We have an Ikea Expedit bookcase in our home, too, but it doesn't look nearly this good. At first we thought this was a paint job, but it's actually easier than that...
The project is a creation of Flickr user Super*Junk (see more photos of her cool space here.) All she did was cover the insides of each Expedite cubby with colored paper and add some lights to show it off. We can imagine using a few different decorative papers or wrapping paper to give the project even more pizazz.
(Re-Edited from 2007-9-21- CB)