I think certifications of that sort are geneneraly overrated, for several reasons. The most important one is that remembering the sort of thing it tests on is unimportant; the only thing that matters is if you can find out how to do it quickly when it comes up.

(I'm reminded of a question on the A+ test, for example (possible I'm missremembering): If you want to start windows in safe mode, what key should you press during boot: F3, esc, del, or F5. My answer would be "hold down control, and select "safe mode" from the menu. It doesn't matter how you do it, it matters that you can do it.)

In any case, I think the best perl certification you're likely to find is also the most meaningless thing in the community. XP. My level is on my resumé. It shows community involvement, and it shows that there's people that respect my skills, which my work history, unfortunately, does not.