Unfortunately, this is an exam, that does not have a dedicated book, that covers all the exam objectives (such as SCJP or SCWCD). So, everyone has to come up with his own set of preparation materials.
This is what i am currently using for my preparation:
1. "Pro EJB 3: Java Persistence API" book my Mike Keith - awesome coverage of JPA 1.0 stuff !
2. "Enterprise JavaBeans 3.0" book by Bill Burke - i use it only for the EJB part of the exam, a lot is covered, but it's not that great as Mike's book.
3. I intend to go through Mikalai Zaikin's notes, since it is the only source that covers all SCBCD 5 objectives.
4. From time to time, i take a look at the EJB 3.0/JPA 1.0 specifications - it's inevitable....
5. I intend to go through the mock exams i have recently purchased, and i hope that they will give me a realistic impression about the real exam. Who knows...
SCJP 6 (86% - the hard way), SCBCD 5 (81% - the hard way)