New from Packt Publishing is HTML5 and CSS3 Transition, Transformation, and Animation. Recommended, but as one of the technical reviewers I might be a bit biased.
From the website:
Instead of wading through loads of theory, the concepts in this book are explained in a practical manner using code samples to demonstrate the new features of HTML5 and CSS3. The code samples are such that you can copy the code (the entire code is written instead of code snippets) and execute it for better understanding. Transition, transformation, and animation are also explained in a lucid manner, and there is a gradual increase in the difficulty level throughout the book.