I am the lead Bioinformatisist (which is as clumsy to say as to type) for a small biotech company. When I got into Bioinformatics, much of what I did was write parsers in Perl, a task for which I was self taught (and not very well I might add.) So I learned by trial and error many of the topics covered in that book. Now that BioPerl is on the scene, many of those same things can be done much more cleanly using community maintained modules.
Now I use Perl for lots of database connectivity, especially tying together data analysis results in a unix cluster to our database on a Windows box.