As mentioned in my previous post I am now Adobe Certified Professional.
If you are planning to appear for Flex Certification Exam following information will help you.

• Go through Adobe® Flex(tm) 2 DeveloperExam Guide to get the overall idea of exam.
• Refer Flex 2 Developer’s Guide This will help you to cover all areas of flex.
• Refer Programming ActionScript 3 for High Level reference of ActionScript 3.0

This is just a reference material but you experience will count.

Exam questions are come from four areas mentioned in Developer Exam guide.

1. Flex Application User Interface (UI) Creation
   IF you have played with most of UIcomponent of Flex you can easily answer the questions. But questions will not be straight forward it will be well twisted so it requires good attention while reading question.
2. Flex System Architecture and Design
   You should have really good knowledge of flex component architecture and must know how to created loosely coupled component. You should also know basic UML diagram techniques like Inheritance, Implementing interface etc.
3. Flex Application Programming Fundamentals
   You need to have knowledge of OOPS programming and Core AS3 programming like String, Array etc.
4. Integrating with Remote Data and Flex Applications
   If you have worked extensively with flex but haven’t played much with data integration with flex then this will be very difficult area for you. You have for prepare and practice well to understand RPC services features for flex and have good understanding of LCDS

Reading is fine for certification but after all “Experience Matters”