The mod_perl2 User's Guide by Stas Bekman (who also wrote Practical mod_perl with Eric Cholet) and Jim Brandt has been released at last. 50% of the proceeds from the sale of this book will go to The Perl Foundation.

From the website:

If you aren't familiar with mod_perl, it's a combination of Perl and Apache. Apache is the most popular free and open source webserver that delivers most of the pages on Internet. Perl is a very popular programming language, that used to be the language of choice for web-programming (though now many other languages are widely used, some more popular than the others). And finally mod_perl allows programmers to develop the software in Perl and take advantage of a very rich API that Apache provides (and which is not available through the CGI interface).

For those of you who don't know Stas, he was one of the key authors of mod_perl2 and was sponsored by TicketMaster for 2 (or more?) years to work on mod_perl. I can think of few people more knowledgeable about this subject.