I agree with everyone's sentiments about certifications *almost* being a waste of time, I think you could get "certified" in a way that would avoid raw memorization.

Test Part I
Basic written exam threading through different topics in regards to perl, more than likely *not* multiple choice. Something along the lines of given snippet A and you are writing sub_function B what would the most memory efficient way be to pass data X over.. With possible solutions being using a ref, or def'ing a local var within scope. Now what about programming efficiency. Now what about maintainability (with possible definitions of "your location" being a perl devel shop, a mixed lang shop, or even possibly a operations/sysadmin facility) Something along those lines. This way you not only display that you know syntax, but that you can also alter your code based on application requirements, and who may be coming along after you, which I think most would agree on can make a big difference in what constructs and idioms get used in the code.

Test Part II Hands on yummy perl goodness. Possibly say 3 portions. First, write simple script/module to do X (possibly dynamically based on what Part I determined your strenghts to be). Second, given script/snippet Y write POD describing its functionality, and interface. If possible also define a BUGS subsection of the documentation, or a TODO list with recommendations for extension/improvment to the code. Lastly, given code Z which does not work and/or meet requirements, fix it to meet criterion A, B, and C

This way you either do well enough on the written to move along to the practical, or you need to go back and study some more. Then in the practical it really is practical, as opposed to more simple memorization. There should be more than enough code out there to use as a base for the cert, and if not, it's not all that difficult to build quasi contrived code for situation X... Thought for Perl Certification shamelessly stolen from CCIE certification exam..

MMMMM... Chocolaty Perl Goodness.....