This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
I don't think Apress has posted any sample chapters, yet. However, you can get a sample chapter from the previous edition, Pro EJB 3 at http://www.apress.com/book/downloadfile/2807. That will give you a feel for the writing style and let you know if it fits with the way that you like to get information. Pro JPA 2 just includes updated and additional content than what is in the previous edition.