This book has been a long time in the writing and it shows in the quality and scope.
From a few pages of code in The Art of Port Scanning, Phrack Magazine in 1997 to Hollywood mainstream in 2003, Nmap became a sub-cultural icon, movie shorthand for hackers and hacking, as well as one of the most widely used security tools. Well, in Nmap Network Scanning, its creator just wrote its biography, and it's very revealing.
This isn't just another "how to use" book, although that is all in there, both in case studies and in a 42-page reference guide. This is the most revealing technical book I've ever read about a security tool. Fyodor turns Nmap inside out to explain what it does, how it does it and why it was written that way. If you are looking for a definitive book on Nmap, this is it.
Anyone fortunate enough to have got hold of one of the pre-release copies at Black Hat or Defcon will not have been disappointed.
There is a wealth of other material on the associated website, including sample chapters for those who want a better idea of the content.