Perl 5.8.x is no longer supported by the Perl community or p5p. The policy discussed in perlpolicy states that the Perl5 Porters support the two most recent stable releases. Right now that means Perl 5.18 and Perl 5.16. Critical security patches will, to the best of the porters ability, go back three years, which means that even though 5.14 is no longer supported for other critical issues, for critical security issues it may still receive updates if it falls within p5p's ability.

Modules on CPAN often attempt to maintain compatibility with older versions of Perl as well. But this is done on a module-by-module basis at the whim of the module's developer. It's not uncommon to see modules that officially support Perl 5.8, 5.6, or in some cases even earlier Perl releases, though that's becoming harder and harder to do as time marches on, bringing with it increased demand for full Unicode support or other "modern" tools that early Perl5's weren't designed to work with.

Some vendors will ship Linux (or other OS) distributions with older versions of Perl, such as Perl 5.8. In those cases, the vendors may support those older Perl versions even if the Perl community has moved on.

I haven't looked into the wikipedia article's sources. One reason that Perl 5.8 may still be the most popular Perl is that it was around so long before 5.10 came along, and then in the years since 5.10 there have been so many other releases. The point being that no single release from 5.10 onward has had time to become entrenched to the degree that 5.8 did. 5.8 was with us for a long time; there was some stagnation during that era. And as I mentioned earlier, some vendors are still shipping it.

This is a topic that borders on religion, politics, and what is the best Scotch (Glenmorangie.)

After reading, and posting, many comments on this, I have come to the conclusion that whenever possible I will write code that will run on 5.8.8 if it is intended for public consumption such as on CPAN. That said, when working in a private, dedicated environment (such as work) where we have full control over what is installed then I feel free to take advantage of whatever features are available with our version of Perl (currently v5.16.)

I concur with the preceding post that 5.8.8 (and arguably 5.8.9) is so common because of the length of time before 5.10 came out. I also agree with the speculation that the frequent updates since then have prevented any single version of Perl (starting with 5.10) since then from gaining widespread acceptance as being the de-facto standard. (I would entertain arguments that 5.10 should be the new minimum version to code to.)

"As of 2013 this version is still remains the most popular version of Perl

If the breakdown of usage is like this:

5.6.1     0%;
5.6.2     1%;
5.8.8     1%;
5.8.9     9%;
5.10.0    2%;
5.10.1    3%;
5.12.0    3%;
5.12.1    5%;
5.12.2    6%;
5.12.3    6%;
5.12.4    5%;
5.12.5    4%;
5.14.0    4%;
5.14.1    6%;
5.14.2    6%;
5.14.3    4%;
5.14.4    2%;
5.16.0    7%;
5.16.1    7%;
5.16.2    8%;
5.16.3    6%;
5.18.0    1%;
5.18.1    2%;
[download]

... then 5.8.9 is the most popular version, even if 90% of people are on more recent versions.

(Note, that these figures are entirely theoretical. I've just pulled them out of the air.)

If you're writing new software, the value of supporting Perl earlier than 5.12 is probably pretty limited. OK, so there are still a lot of people using older versions of Perl, but these will often be on servers which have been sitting around for years, doing the same thing without any changes the whole time. The people running these machines are unlikely to be wanting to install your shiny new software anyway, because their box is running-just-fine-as-it-is-thank-you-very-much.

There is some statistics which correlate with perl version popularity: cpanminus version stats