Nothing much except, that I looooooooove this book. Just on the second chapter but I already feel empowered to tackle the dreaded CSS Liquid layouts. I have always avoided them as I was unsure how to make them intergrete with images and still remain fluid as well as making sure they do not break.
All right, if you insist, I will explain more ...
One of the best computer books I ever ready. Highly recommended. Is it going to teach you CSS? Nay, it won't, so you need to be confortable with CSS not necessarily a pro but you should be able to craft out a basic 2, or 3 columm from SCRATCH. Basically you should be able to pull things from the default browser rendering and positioning them. The book goes step by step as you build a liquid layout (code available from companion site) so you will still be able to fill your gaps in case you do not know the 'clear' feature in CSS. An excellent book with 200 to 280 pages, so it wont be long before your web pages are flexible.
Update: Adding images to a liquid css layout is one of the biggest headaches for css coders. There is a section that explains prepare images that will stretch as the layout stretches by segmenting a large image into multiple sliding pieces.