Hi: A very interesting writeup on CGI and mod_perlite on OReilly site.
Summary . CGI is a technology and protocol well suited for certain types of applications. . PERL and CGI are closely interlinked. . "upload and run" simplicity of hosting environments . PERL can run but a module that the webapp needs is missing (that reminds me of bugzilla :) ) . mod_perlite is inspired by mod_php, as mod_php had solved many problems that CGI apps face. . mod_perl is a very robust and enterprise grade apache module. . PHP is used a front end on many large websites. For the rest of insights, please take a look at http://broadcast.oreilly.com/print/35007.html thanks Saifi.
