Perl 5 -- the current version of Perl -- is fourteen years old now. It's had several major revisions in that time. (See Perl History for more details.) These major revisions add new features, fix old bugs, and generally improve the language. All of these changes come from real-world users who use the language themselves.
The current stable major version of Perl is Perl 5.10, released in December 2007. This release includes several features backported from Perl 6, the next stage in evolution of Perl.
Perl's a popular language. It's been around for 21 years, and it was the language of server-side programming back in the day. It's still popular. There are hundreds of books and thousands of tutorials available all over the Internet. You can learn Perl with little more than a text editor and a web browser, if you so desire.
Remember, however, the Internet rarely forgets. A Perl tutorial which represented the best version of Perl from 1991 may still be around -- and thanks to search engines, it may be the most highly recommended tutorial anywhere. Eighteen years later, Perl's moved on. We've learned a lot since then.
The best way to write Perl programs in 1991 or 2001 or 2004 isn't necessarily the best way to write Perl programs in 2009. It's time to discuss and document and disseminate all of the wisdom of the greater Perl community. It's time to talk about modern Perl.