Certified MySQL Associate (CMA)
This is a beginner level certification designed for those new to databases, SQL and MySQL. One 50 question exam is required.
Certified MySQL DBA (CMDBA)
For database administrators who can install, troubleshoot and maintain databases. Requires two exams, each with 70 questions.
Certified MySQL Developer (CMDEV)
For developers currently using MySQL databases who can export data and perform somewhat advanced reporting. Requires two exams, each containing 70 questions.
Certified MySQL Cluster DBA
For MySQL Cluster DBAs who have had practical experience performing continuous service on cluster setups. Requires a CMDBA and one 70 question exam.
All exams cost US $200 and are available through VUE.
MySQL publishes the MySQL 5.0 Certification Study Guide for the exams and offers training. The study guide is available through most bookstores and costs around $60 (although I found it on Amazon for $35). The book includes a 25% discount on the exams and lots of practice questions. More information and a sample chapter.