Oh, I've forgot about this one. I should read it, when I'll have spare time.
I really like Kurzweil, whom I consider being a visionary, because he takes known facts, uses known logic on it, and gets conclusions, which nobody would ever think about. Also, he's the only futurologist I know, most of whose predictions came true.
By the way, here's the list of some other good books I've enjoyed (not quite relevant to the topic, but still a pleasure to read):
Stephen Hawking - A brief history of time
Stephen Hawking - The universe in a nutshell (re-release of the previous book in the list, which has many more topics covered) - a nowadays concepts of the world (from "classic" things like theory of relativity and quantum physics to a modern things like string theory, universe as a hologram [hello, YK!], multiple histories, time travel, and so forth).
Michio Kaku - Physics of the impossible. An awesome book about concepts found in science fictions and how they can be implemented in reality (if they can be implemented).
Eric Drexler - Engines of creation. Nanotechnology and everything about it.
Ray Kurzweil - The age of spiritual machines. - Self explanatory.
Stanislaw Lem - Summa Technologiae. An old (from 60s) book, but is quite relevant even nowadays. It's like Kurzweil, but from a Soviet point of view.
And the best about this books is that they are written for usual people - you don't need to have a deep knowledge of physics to understand them. They're really easy to read and they explain very complicated things in a simple way.
The best way to describe it is this quote from wikipedia:
[About Hawking's "The universe in a nutshell"]
The author notes that an editor warned him that for every equation in the book the readership would be halved, hence it includes only a single equation: E = mc^2.