1. The second edition of the official Sun guide is about to be published: http://humphreysheil.blogspot.com/2009/09/addressing-rough-cuts-feedback-received.html
The first edition is very good but is somewhat dated for this version of the exam: http://www.amazon.com/Certified-Enterprise-Architecture-Technology-Study/dp/0130449164
. It does not cover all sections of the exam though.
2. The GoF book is a must have for any aspiring architect or even mid-level developer - "Elements of Reusable Object-Oriented Software"
3. Same for this one: "Core J2EE Patterns: Best Practices and Design Strategies (2nd Edition)"
There are a couple of good books that can be downloaded for free:
4. "Mastering Enterprise JavaBeans 3.0" by Rima Patel Sriganesh, Gerald Brose, and Micah Silverman - very detailed on EJB and JPA. Make sure you don't get one of the earlier editions (Roman).
5. "The Java EE 5Tutorial" (Sun Microsystems) - surprisingly good and comprehensive. My primary source on JSF.
Finally a couple of books that could be useful for the assignment (Step 2):
1. "UML Distilled" (Fowler)
2. (optional) "Building J2EE Applications with the Rational Unified Process" Although RUP is not required, some of its ideas will help you structure your project (and your thoughts) better. Specifically use case realizations (sequence diagrams) and domain model. Reading up on Software Architecture Document also gave me a lot of food for thought. However, be warned that following the entire process to the letter can lead to "process paralysis" even on a real project.