I consider myself a seasoned perl programmer, and I use the book too. A lot. The only thing I added as a printer minipage is the output of

$ perldoc perlcheat
[download]

after making a few small changes to include the things I keep forgetting, and a peek-a-boo section on open my $fh, "| command" vs open my $fh, "|-", "command"

Note that the regular expression section content changed a lot since PPR4!