As of current planning, the book should be available by late April. The physical copy will cost $27 from Amazon (and qualifies for free super saver shipping), while an e-book for the Kindle will cost about $10. For right now, the physical copy is only technically available on the US Amazon site due to constraints with Createspace, the print-on-demand publisher I'm using, though copies tend to filter to international sites like Amazon UK over the course of a few weeks. The Amazon US site should ship overseas, though.
Please check out the HG101 Presents: The Guide to Classic Graphic Adventures page for a full table of contents, as well as some history behind the project, what our goals were, what it entails and why the coverage was shifting towards adventure games (and PC titles) for quite a while. Hopefully this will be first in a series of gigantic catalogs of retro gaming! Here is a sample PDF of roughly 30 pages or so.