There is another side to this as well. I'm a developer that works in a mainly Windows environment. I'm slowly converting those around me to Linux. Anyway, people know I can get things done in Perl when no one else seems to know how to go about it. If a project I'm working on requires GPL code, I'm delighted since I am legally obligated to make my source code available. I don't have to worry about a boss telling me not to. This gives me the freedom to both accomplish the task at hand and to contribute to the community.
Its easy to think of modules as add ons to a program but its only in source version that any such distinction can be made. I suppose if the Perl compiler you use can compile the modules separately from the propriatary code then there would be no violation of the GPL, but if there is no such separation in the binary then I don't see why the GPL shouldn't apply. If there is some distinction in the binary then you could argue that you were simply using the modules and not modifying them or building something off of them. (Much like it isn't a violation of GPL to run propritary code on a Linux system). Maybe what we need is a fancy compiler like this. All the same, if you do use free software, remember to give back to the community. I'm a little surprised that a company would be both taking advantage of open source and then distribute a propritary product. Think about all the reasons you use an open source language like Perl... can you honestly say that those same reasons won't cause your clients to prefer an open source solution? - Johnathan
