I don't use CGI.pm any more. (Though I did recently write a CGI script. I used Plack for it. I ♥ Plack.)
As usual, Aristotle is right. Plack is an obvious improvement to deploying Perl web applications and a very powerful way to manage middleware concerns. I use it with multiple projects.
I keep toying with the idea of producing a little book on Plack. It can be a short introduction to what Plack is (and why Plack is), a guide to some of the deployment options (such as when to use the various backends), a set of examples of the best middleware which exists today, and a guide to writing your own middleware or server backend.
It should be short. It can be succinct. It doesn't have to be a three hundred page, $35 printed book. It could be a hundred pages long, electronic format, and available for less than $10.
Does this interest anyone besides me?
(Other books are coming too, oh yes, probably including an update to Modern Perl for Perl 5.14.)