So, I just passed the SCJA today and thought I would give some insights since I found many of the posts on here helpful.
1) The vast majority of the questions were related to either:
a) Interpreting code examples and outputs: Know your nested loops, static methods, String objects,etc. VERY well. 3 questions were related static methods not taking instance variables. Many others involved answers that would not compile and you need to specify the line. This felt like about 20 questions.
b) Java Technologies:. J2EE, client and server side stuff was about another 20 questions it felt like (too many if you ask me) so you'd BETTER know this. Some were hard, but most weren't too detailed. It was pretty much everything. JSP, Servlets, JNDI, JDBC, EJBs, ... About one questions for EVERY technology on the objectives list.
2) There were NO questions about UML. Not one.
3) The few object-oriented "theory" questions were very elementary questions. The more difficult ones involved examples of code.
4) A few easy questions on -d, -D, and -version.
I thought it was overall slightly easier than the practice exams from Enthuware or McKenzie's book, so if you can ace those you should pass for sure.
Focus on understanding code "tricks" and technologies and you should nail it.
I just passed the OCAJ SE 5/6 with an 88% and had a very similar experience to Scott. UML is no longer covered, but I did have about 5 questions on javac and java on the command line, but unlike Scott some of mine were a little tricky, like moving packages bwt directories and stuff.
I had like 20 code example problems about sneaky stuff like pass by ref for primatives, or directional assocition being an object passed in as a parameter.
I had a lot of stuff that wasnt uber tricky just the key points the books tell you to learn, but about 5 question on Java EE and what tiers or containers worked with which parts had me stuck (like web services or Java Mail).
Last I'd say make sure you know where pretty much everything resides, like java.util having Lists and lang.sql NOT housing JDBC.
I read HeadFirst Java over a ccouple months, as I knew no Java at the start, so this OO stuff blew my mind. If this is you, too stick with it, you can get it as you get more exposure (like the two books mentioned just below helping me wrap my mind around this stuff).
I read Kamren Mc.'s book and went thru the questions and practice exams in the book the other 2 guys wrote together. Then i did 3 practice exams from Sun that my work paid for. As i took each test i wrote down the correct answers to all the ones I got wrong and then went over that stuff for 30 min in the car before the exam.
Hope that helps any folks whose work isnt quite up to the Java 7 stuff yet but still want to take the old exam.