I cannot imagine not having Programming Perl on my shelf, along with Perl Best Practices. It would be like claiming to be a Christian even though I did not own a copy of the Bible. The Camel Book is our
bible. Get a copy and stop wasting our time with these blasphemous questions! :-)
All joking aside, the fundamentals haven't changed except maybe in a few more advanced areas. The book is still extremely relevant today, to the point that I think a Perl 5.8.x companion book would make more sense than a Perl 5.8 based Fourth Edition. If you can get it at a good price then by all means do so!