It's been noted that many of the greatest advances in computers, during the past 35 years, were made because brilliant people watched Jobs' speech and worked very hard to make his predictions comes true.
Jobs, of course, was (in part) describing Alan Kay's DynaBook, which Kay envisioned in 1968 and described in a 1972 paper. Kay was an Apple Fellow in the early days of the Macintosh -- his visionary ideas often preceded and inspired Jobs' own.
Yes, true. But Jobs went on to describe how he would build one and gave estimates on what it would take to do so and how it would work. Unfortunately, Apple tossed him out of the company and set him back on his plans, until he later returned to Apple. The end result was the iPad and iPhone (he was actually working on the iPad before the iPhone, but released the iPhone first).