I took the MySQL Core Certification exam yesterday, and passed. It was a tough exam, a bit too picky about edge cases, I think, but I passed. The NDA pretty much forbids me saying more about the exam. Fair enough. The exam is only valid if the Q&A aren’t published, otherwise, the value of the exam and certification plummets, as happened with “paper CNEs” and “paper MCSEs”.
The MySQL folks don’t seem as constrained by the NDA, and post a “real life story” as well as point to two blog entries. That ought to give you a pretty good idea of what’s involved. I’ll wait a while before taking the Pro certification, as it’ll require a few weeks of dedicated night and weekend studying, but I think that’s the proper level of certification for a software development consultant like me to have.