It's nice to see someone write a usable reference guide to PGP/GPG that's not 10+ years old, referring to versions of the software that don't exist any more. Even better in that it's an enjoyable read... PGP & GPG: Email for the Practical Paranoid by Michael W. Lucas.
Contents: Cryptography Kindergarten; Understanding OpenPGP; Installing PGP; Installing GnuPG; The Web of Trust; PGP Key Management; Managing GnuPG Keys; OpenPGP and Email; PGP and Email; GnuPG and Email; Other OpenPGP Considerations; Introduction to PGP Command Line; GnuPG Command Line Summary; Index
When I last had any interest in PGP, you could download the PGP package from just about anywhere and everything was run from the command line. Now PGP is the commercial version of the package, and the OpenPGP implementations are the ones you get and use for free. Lucas does a very nice job in explaining the differences between the commercial and open source implementations, as well as how the commercial implementation's GUI makes much of the command line hassle a thing of the past. On top of covering the GnuPGP version of the open source option, he also covers Windows Privacy Tray, or WinPT, which provides an add-on GUI to GnuPG. The email chapters show how PGP can interface to Microsoft Outlook Express, Microsoft Outlook, and Mozilla Thunderbird. Being a Lotus Notes/Domino user, I would have liked to know about any potential integration packages there, but I'll overlook that slight. :)
Another positive feature about the book is that he doesn't stop at the nuts and bolts of the software. By going into the basics of cryptography and the "Web of Trust" for identity verification, Lucas helps the reader understand the mindset of privacy and the responsibilities one has once they join into that community. Granted, PGP/GPG is nowhere close to being a package that Aunt Mabel will install and understand. I think that by choosing to use this type of encryption, you already have a fair understanding of which end is up. But armed with the proper knowledge and mindset (which you'll get here), you'll be able to make a much stronger contribution to the common good.
If you use PGP or have wanted to venture down that road, or if you're dealing with information that might not be viewed favorably by certain authorities (regardless of what you may morally believe), you should get a copy of this book. It'll save you time in trying to piece it all together on your own, and it's light-years ahead of the other (aged) books on the subject.