Peter S. Magnusson has an article discussing recent worldwide employment and productivity figures, and notices an interesting milestone. Worldwide, the percentage of people who earn a living via agriculture (versus service and industry) fell from 42% in 1996 to 36% in 2006. Just over one in three people worldwide works to feed the world, a reversal from pretty much all of human history.
It's an especially interesting subject to read, since I've been reading S. M. Stirling's Dies the Fire, a novel where technology suddenly stops working, and people must revert to living as they did in the Middle Ages. It's an interesting book, and enjoyable to read because it focuses on two groups who manage to build their pre-industrial worlds, rather than on the billions who will die.