This is a very clever extension to WWW::Mechanize that allows you to simulate a CGI environment without actually running a web server. Instead, the module (via the HTTP::Request::CGI helper) sets up the proper CGI envvars and runs either a CGI file or a wrapper function.
My only complaint (and that's high praise for a v0.2!) is that there is no cookbook for commonly used CGI idioms. I've posted a couple of hints myself at annocpan.org/