Each week Ross Rubin contributes Switched On, a column about consumer technology.
When Apple introduced the iPod in 2001 -- some 250 million units ago, as Steve Jobs noted -- it began with a laser-like focus on digital music. Swap out a hard drive and FireWire port for a cassette collection, and the product was clearly the reinvention of the Walkman. The first Switched On in 2004 pondered the iPod photo as a stepping stone to video. And by 2007, the iPhone and iPod touch had become capable of playing a broad array of content and would soon be
