On Friday I took and passed the Oracle Certified MySQL 5 Associate exam, which covered all the MySQL 5 basics.
My preparation only really involved the use of the MySQL 5.0 Certification Study Guide (up to page 300ish) making some notes and playing with the standard mysql client in Linux to test some new / niche things out. Additionally the MySQL Manual came in handy for reviewing functions and transactions.
Not really allowed to discuss the exam questions (due to a standard NDA) but after so much reading I didn’t seem to have much difficulty, but that of course follows. MySQL is not a difficult subject in general, there is simply a lot to learn.