I would agree that an AI book would be useful. Modern AI fields, such as machine learning and statistical learning theory, are barely represented in the Perl world and a book including them would be useful for the new modules and module tutorials, if nothing else.

As long as we are wishing, I would like a book on Numerical Methods and Scientific Computing for Perl. Between PDL and the many mathematical modules on CPAN, I think one can make a good case for Perl as a scientific scripting language (I have done so for many years). Mastering Algorithms with Perl touches on numerical topics, but can't be considered a full numerical manual.