Won't Perl6 make the book redundant, I mean the whole reason we needed a Modern Perl book was because there was an old and crufty way of writing Perl5...but Perl6 ditched all that baggage so the only way to write Perl6 will be comparable to Perl5's "modern Perl" paradigm?
Modern Perl book was first released a few years before P6, which isn't even released yet. The companies that currently use Perl (at $work, even) are not going to switch to P6 any time soon, but can, and do benefit from the more recent best practices using Perl 5.