I received this tome by Ray Kurzweil in the mail recently. Can’t say much since I just started reading it, but as a non-fiction science book it looks both exciting and intimidating. Some other recent books of similar interest include: Ramez Naam’s More Than Human : Embracing the Promise of Biological Enhancement, Ron Bailey’s Liberation Biology, Gregory Stock’s Redesigning Humans: Our Inevitable Genetic Future, and Joel Garreau’s Radical Evolution : The Promise and Peril of Enhancing Our Minds, Our Bodies—and What It Means to Be Human. I have a copy of Bailey’s book, which is next on the reading list, and of the others Garreau’s looks compelling. 
An interesting discussion of this book is at Pharyngula.
Great link. Skepticism is always healthy. The Singularity appears to be an ideas whose time has come, and I think we’ll see more books like this. I read an interview with Damien Broderick, sf author and critic, who tried to popularize the term “the Spike.” Charles Stross calls this event “the Rapture of the Nerds,” so in the end this may be nothing but a variant of tehcnological millenarianism.