I don't think CPAN itself has these stats, but you asked in the right place. If someone has already collected such info, you probably can find her/him here.

If CPANTS were up, you could look for Moose and look at the distributions that depend on it. But it is not working (at least for me).

With regard to very popular modules, the Phalanx Project has a (possibly outdated) list of the 100 most popular ones.

And then there is Google Search Code, but it doesn't summarize its findings (yet). Or maybe I don't know the last news. Try http://www.google.com/codesearch?q=Moose+lang%3Aperl&hl=en&btnG=Search+Code.

Update: got the link to the Phalanx project right, thanks to j3's Re^2: Which CPAN modules are most used/depended upon?.

Note, that link is http://qa.perl.org/phalanx/. Their faq describes a bit how they chose the Phalanx 100. The list is said to be "based roughly on popularity and importance".

I believe perl.qa is the Phalanx ML.

I like their slogan: "You carry your helmet for you, but you carry your shield for the entire line." :)

This is an interesting question. A few days ago I wondered myself about Moose. Please let us know if you find something. The hard way would be for each distribution on CPAN to look for the META.yml file and count prerequisites building a global hash (o dbm-like file). If there is no *yml file (case of older distributions) you'll have to parse Makefile.PL (o Build.PL)I guess. In the case of Makefile.PL, you can redefine WriteMakefile to simply return a list, convert it to hash, and use the PREREQS_PM entry (not tried, but seems easy enough...)

I really wish there were some opt-in statistical reporting for CPAN. Personally, I'd like to see if people are using the stuff I wrote, but it'd also be neat to see which modules are really popular so I could check them out. Unfortunately, I don't think anything like that exists.

Personally, I'd like to see if people are using the stuff I wrote,

That's easy. Look at the size of your rt.cpan.org queue. If it's empty, either your code is perfect (unlikely), or nobody is using it or cares about it.

-- Randal L. Schwartz, Perl hacker

That's definitely an indicator of something, but not really what I had in mind. I don't think rt.cpan.org is really that popular yet. In addition, if I am personally an example of a human, then I figure most people that experience a problem with a module simply code around it or email the author. The only person that's ever re-directed me to rt after an email is Mr. Tang, the the author of PAR.

The author of Convert::ASN1 (for example) just fixed the problem and released a new version. I noticed that the only tickets open on that are spam with a couple real ones from 10 months ago. I have a hunch Mr. Barr doesn't even know rt is there, nor do most of the module's users.

Don't get me wrong, I can't wait for rt to take off. It's really slick. But I don't think it's a very good indicator of whether people are using your modules yet.

-Paul

Let me start with a disclaimer, I am the author of Moose, so any opinions here might be a little biased ;)

Specifically, I was wondering how many OO modules are using Moose.

By searching for "Moose" on http://search.cpan.org, then looking at the META.yml and Makefile.PL files, I found the following:

• Class::Workflow
• Mail::Summary::Tools
• POE::Component::DirWatch::Object
• Date::Biorhythm
• Class::Component::Recipe
• Reaction (the CPAN version is a very early release of this, go to #reaction on irc.perl.org for more info)
• WWW::Facebook::API::REST::Client
• Verby

In addition to these modules, we have been using Moose quite a lot at $work. We use it both in the refactoring of older code (I spent a few days once just replacing hand-coded accessors with Moose attributes), and in producing new code. But as I said above, I wrote it (and $work sponsored that effort), so of course we are gonna use it.

I know of several other people who have used Moose successfully at $work as well (passing code reviews and deplying successfully to production). And there seems to be a fair amount of people in the POE and Catalyst communities who are playing around with Moose too.