The Symfony blog has a new post with links to some books to help you work with the latest version of the framework - Symfony 1.3/1.4.
The symfony 1.3 and 1.4 final releases are just around the corner, and will probably be published next Monday. As you might have noticed, the symfony documentation have also been updated to take into account the changes made in those two new versions.
They mention the books "Getting Started with Symfony 1.3 & 1.4", the "Symfony 1.3 & 1.4 Reference Guide" and "Practical symfony 1.3 & 1.4". You can either read the contents of them online or you can order them directly from Amazon as a published book.