Today I took the SCBCD certification exam and passed missing only one of the questions (it was one on
EJB 3.0 fundamentals).
I have began preparation in June, so it took me 4 months and a half more or less. I began preparation reading O'Reilly's book but continued by going through the specs. I don't know how to stress it properly, but reading the specs is fundamental for this exam. Some of the questions on it are taken directly from paragraphs of the specs. I would recommend people preparing for the SCBCD certification to at least read chapters 3 (not necessarily EJB 2.1 client view part), 4, 5, 12, 13, 14, 16, 17, 18, 19, 20, 21 and 22 of the ejb core specification, chapter 9 from the ejb simplified specification and chapters 2, 3, 4, 5, 6, 8, 9 and 10 of the ejb persistence specification. I have read the mentioned chapters at least twice and in some cases thrice or more. Really!
For practicing, while I was reading O'Reilly's book I used
JBoss but as soon I started reading the specifications I changed for Glassfish. I would recommend people to use the latter, as it is the reference implementation.
Finally, I finished my preparation by doing Enthuware's mocks. I'd say this was a very important part of my preparation. My impression is that the real exam is a little bit easier than these mocks (I scored 77 in the first two, 80 in the third and fourth and 85 in the 'last day'
test).
I also wanted to thank the people in this forum that helped me answering my doubts.