This YAPC, SANFACE Software had a talk entitled Can a Company Use Perl to Develop - and Sell - Commercial Tools?.
I was interested in that. I knew of their application txt2pdf, which is shareware, from reading comp.os.linux.announce digests, and was interested in hearing what they had to say about their experience about making money off software which comes with source code.
However, I was a bit disappointed with the talk. To me, it seemed like mostly whinging about how "the Perl community" (whoever he is) wouldn't let them advertise their product because "the Perl community" doesn't like shareware or payware, and also about how they were disappointed that no-one wanted to learn from their experience with this marketing method.
Another piece of payware which provides Perl source code (as I understand it) is Radiator. I wonder whether they've ever compared notes with them?
And besides, one of the people in the audience made a comment which I think was insightful -- "The Perl ommunity is not your audience. Not many people would buy your software just because it's written in Perl. Try marketing to your audience -- the people who would use the program." Maybe librarians or someone? At any rate, I think that's true. I somehow doubt that comp.lang.c is flooded with product advertisements justified with "it must be on-topic because the product is written in C".