I'd be curious to hear if the audience is at all Perl savvy? And even if they are, whether they can process any code beamed onto a screen?

On a number of occasions, I've listened to, and given, presentations to a mixed crowd of programmers (java/python/perl/ruby/etc), and regardless of the language, people just can't handle staring at code. Even python.

I second that, at most, you'll want to have three lines of code per slide (I'd go with pdf files, by the way - from latex, or html or whatever, but it just seems the most portable).

Perhaps fill your slides with flowcharts (UML), inheritance trees (doxyperl) and stuff like that instead? It's easy to assume people can pick up all the stuff that you have inside your head and jump right into parsing code that applies to your problem domain, but that just never quite happens.