Slides: Mobile is Eating the World from Quartz provides a high-level yet in-depth set of slides showing how mobile computing is eclipsing desktop computing.
The presentation has 73 slides covering all things mobile computing. But the slide below, which shows PC unit sales (light blue) versus smartphone and tablet sales (yellow), provides a nice summarye
Kudos to the author - Ben Evans - for creating this presentation and making available to the public. His website is full of useful information on mobile computing and I've added it to our "must follow" list.