I left out one detail -- sort of on purpose, for which I apologize. My recent work was in Java where I needed the reflection package to have a hope of completing the task. Our goal is to be able to generate and use the YAML data in java for day to day work while turning to perl to handle disasters in our clients.
My definition of introspection or reflection, which I take as synonyms, is anything a Java programmer would need the reflection package for. Perl provides many different syntactic ways to reach the same effects, I call all of those reflection. Thus, in my book, using a string to bless an object into someone else's class is reflection.
The most popular reflection users these days are then Object Relational Mappers (ORMs). They need to manufacture classes at run time, for this they need the language's reflection system.