Comments about O'Reilly Media mod_perl Pocket Reference:

This little guidebook goes out of its way to say what it isn't -- "this is not meant to be a guide to so-and-so" -- and yet it does an excellent job of giving an overview of mod_perl, cgi, and apache, including the role and functionality of each and how you can leverage them. Samples of some of the code would be appreciated, but then the format of the book doesn't really allow this, and that's okay -- you can turn to more thorough manuals for that.

For a quick introduction to the subject, an overview of why you should be using mod_perl instead of standalone scripts, and a pocket-sized pamphlet that you can turn to for reference once you have more experience with the material, this book should be a fine choice.