Per my presentation on responsive design at Lavacon on Monday, here are two books that I'd immediately recommend on responsive design and CSS.
- "Implementing Responsive Design" by Tim Kadlec, New Riders. Written more for programmers than help authors, but I'd recommend this book for the people at the presentation who were looking to go beyond what a help authoring tool can do through the GUI.
"The CSS Pocket Guide" by Chris Casciano, Peachpit Press. A easily digestible summary of the depths of the Cascading Style Sheet standard.