I just began reading O'Reilly's Learning Perl, 6th Edition and was surprised when I came across this excerpt.
#!/usr/bin/perl print "Hello, world!\n";
Let’s imagine that you’ve typed that into your text editor. (Don’t worry yet about what the parts mean and how they work. You’ll see about those in a moment.) You can generally save that program under any name you wish. Perl doesn’t require any special kind of filename or extension, and it’s better not to use an extension at all.
Why is it better to have no extension? Imagine that you’ve written a program to calculate bowling scores and you’ve told all of your friends that it’s called bowling.plx. One day you decide to rewrite it in C. Do you still call it by the same name, implying that it’s still written in Perl? Or do you tell everyone that it has a new name? (And don’t call it bowling.c, please!) The answer is that it’s none of their business what language it’s written in, if they’re merely using it. So it should have simply been called bowling in the first place.
This is the only source I've seen with this view, everything else I've read has supported the .pl extension. I'm no Perl programmer yet, and I wanted to know what the community's view on this was before I got into a habit.