You can use the 'search' facility in the Programmer Certification Forum with the keyword 'IBM' to get all IBM related discussion threads. You have to register first to get the mock Exam paper. Worth to take . Upto 36 qstns are written properly. All answers are not given.
Questions are good.
Exam from Sun. So if you take this test and get low scores don't be upset. But their 'Java Certification Book' seems to be really good. I hadn't bought this book. But from others comment this book is more than just a Certification book.