How do large companies such as Apple Computer continue to innovate and respond rapidly to new opportunities, as if they were start-ups?

Apple seemed to produce the iPod out of thin air in 2001 – at the time, a personal digital music player was not regarded as the obvious progeny of a personal computer manufacturer. Yet the company has since re-entered the FT Global 500 ranking of the world’s largest companies at number 159, after a four-year absence.