Last spring it dawned on Apple CEO Steve Jobs that the heart of his hit iPod digital music player was the "shuffle." This feature allows users to mix up their entire song collections—thousands of tunes—and play them back in a jumbled order, like a private radio station. Jobs not only moved the popular shuffle option to an exalted place on the top menu of the iPod, he also used the idea as the design principle of the new low-cost iPod Shuffle. Its ad slogan celebrates the serendipity music lovers embrace when their songs are reordered by chance—"Life is random."

But just about everyone who has an iPod has wondered how random the iPod shuffle function really is. From the day I loaded up my first Pod, it was as if the little devil liked to play favorites. It had a particular fondness for Steely Dan, whose songs always seemed to pop up two or three times in the first hour of play. Other songs seemed to be exiled to a forgotten corner of the disk drive. Months after I bought "Wild Thing" from the iTunes store, I'm still waiting for my iPod to cue it up.