If you are looking for an architect-level view of how GWT can best be leveraged by your enterprise projects, Pro App Development with GWT is a great resource. The book goes through the steps in designing a robust Web 2.0 application using Spring, Hibernate, Lucene, and GWT. The finished application can be viewed online at www.tocollege.net.
For developers like myself who have worked with small-scale GWT projects, this book directly answers many of the issues that one encounters when scaling up the project. Examples of these issues are: the most effective way to pass Hibernate classes back to the client using GWT, and how to most efficiently handle a large project through either single (or multiple) modules.
Please note that this book will not teach you GWT; if you are not familiar with GWT, other books (or even the GWT website) would be superior resources.
The only two issues I had with this book were:
* It would be nice if there was chapter-by-chapter source code available so you could more easily mimic the steps in creating the application. Matching the chapter-by-chapter progress to the final source code was a little tedious.
* The author's choice of technologies for the back-end is great (Spring, Hibernate, FreeMarker templates), but if you are an EJB/JBoss/Seam/Wicket shop, you will be doing a lot of translation from the Spring-domain to your particular choice of technology.
Overall, this book is highly recommended and will make deploying GWT much easier on medium and large-scale projects. The author has done a great job in solving common GWT problems; issues that an enterprise architect will surely encounter when using GWT.