Printing books on demand, printing one copy at a time after they have been paid for, has been around for awhile now. You can go to a traditional bookstore and order one. But soon you will just be able to get the book instantly - literally "hot off the press" at a coffee shop or wherever one wants to stick one.
Here's what it say at the On Demand Books website:
"On Demand Books LLC (ODB) uses proprietary software and a patented, fully integrated high speed machine to print, bind and trim a library quality paperback book at point of sale on demand in minutes at low cost from digital files. The Espresso Book Machine replaces the centralized supply chain for the distribution of books - essentially unchanged since Gutenberg - with radically decentralized direct-to-consumer distribution. In essence, an ATM for books."
My publisher will be involved in this as it developes. I am very excited. A person can grab one of my books in Egypt, or Australia or Canada or New Orleans and Michigan (a few of the places prototype versions of this machine already exist) without waiting for shipping.