The rainbow effect (photoelasticity-the effects of stress, such as double refraction, on the optical properties of transparent materials) is well documented with the iPod – some suffer from it more than others and your ambient light conditions will make it appear worse. In a nutshell – stresses in a clear material cause polarized light to bend and colors to seperate as it passes through the material. Thus, if you have a defect of some sort in your iPod’s screen, when you are in polarized light, you will see a rainbow appear across the iPod. It just so happens that when the sun is lower on the horizon, it tends to polarize (read- wintertime sun).
I'm a passionate, long-time lover of Apple products, and was a civil draftsman and graphic designer before creating the iLounge web site. My prior projects include work for The Los Angeles Times' LATimes.com, and the company Creative Domain, where I developed websites for clients including Columbia Pictures, Disney, Fox Studios, Universal Pictures and Warner Brothers. As the Publisher of iLounge, I direct the site's community forums, photo galleries, iPod User Group, and general business affairs, which have grown under my watch to over sixteen million page views every month. I'm happily married with one daughter, one dog (Rocket the Wonderdog), one cat (Ferris), many iPods, iPhones, iPads, and two turntables.