I am a pure Perl developer - at work anyway. My role in the configuration management team of a very large technology company.

We use a pure Perl solution to implement our inhouse development and release processes on top of various CM systems. We also use a pure Perl solution to manage our compilation proceseses for various large software products.

... and for this, Perl does the job wonderfully well - if only because we use multiple platforms! I have worked for two other companies doing a very similiar thing, so in my experience, Perl is frequently used to implement custom CM and build processes.