I'm about 1/3 of the way through writing the book. Since I announced the project last month, I've submitted chapters 1, 2, and 3. They are in various stages of review by No Starch editors and my technical editors. I seem to be writing more than I expected, despite trying to keep the book at an introductory level. I find that I want to communicate the topic sufficiently to make my point, but I try to avoid going too deeply into related areas.
I'm also encountering situations where I have to promise to explain some concepts later, rather than explain everything immediately. I believe once I get the first chapter ironed out with the editor, the rest will be easier to digest. I'm taking a fairly methodical approach (imagine that), so once the foundation in chapter 1 is done the rest is more straightforward.
I'm keeping a fairly aggressive schedule. Basically I have to write a chapter each week, get it to my technical editors, and then spend additional time working with No Starch to get the text legible and ready for print. All of this is happening in parallel in order to have the books in print by Black Hat. That means the text must done by the first week in April. My family is helping me stay on track by giving me time and space to write, especially on the weekends. Thank you!
When working on the examples, I've been very pleased with the performance of VMWare Workstation 9. I have one copy installed on Windows 7, where I write with Word. I have a second copy installed on Ubuntu Server, where it acts like a "VMWare Server." I used to run a real ESXi server on server-class hardware. Now, to save electricity and to more tailor my computer power to my requirements, I run a Shuttle DS61 with a Core i5-3450S 2.80GHz CPU, 16 GB RAM, 750 GB HDD, and two onboard NICs. The two NICs are really awesome in a device this small -- 190(L) x 165(W) x 43(H) mm. With two NICs, I can devote one for management and one for network traffic collection and interpretation. I use a Net Optics Dual Port Aggregator Tap for access to the wire.
I use VMWare Workstation this way. I run a Linux VM on Workstation on my Windows 7 laptop. I connect via Workstation to the Workstation instance on Ubuntu on the DS61. Then I create whatever VMs I need on the DS61. For example, I created a Security Onion server and sensor to test that setup. With 16 GB RAM, I have plenty of RAM for both, plus another VM that I'm running as my "production" Security Onion sensor for the lab network.
Writing is going well, despite the fact that I last wrote a book in 2005. I promised my youngest daughter, who wasn't born until 2006, that this new book is for her. If you have any questions on the writing process, please post them here or ask me on Twitter.