Depends what you mean by widely-used. After Rails and Django appeared I can't remember many high-profile sites using any of the Perl frameworks. Maybe Catalyst at the BBC and Net-A-Porter who hired a lot of Perl gurus. Perl's realy failure was competing with PHP. Perl's equivalent, HTML::Mason, really required mod_perl to perform anywhere near mod_php and that's what killed it as mod_perl was not an option for cheap hosting providers. PHP was as much a marketing coup as anything else, hence Facebook built on PHP. I think it says everything that Dustin Moskovitz mistakenly picked-up a Perl textbook before he was corrected by Mark Zuckerberg that they were using PHP. That's exactly where Perl stood in relation to PHP in early 2004.