A group of C hackers who write the Perl programming language. The name comes from the fact that one of their big jobs is "porting" Perl 5 to various platforms.
"p5p" is a very active group. It has several hundred subscribers and several dozen regular contributors. It's not unusual to get 500 messages in a week. Even more amazing, little of this is automated. There are perhaps a dozen automated "smoke test" results a week, and a few bug reports; otherwise everything is human-written, mostly discussion on features or bugs and source-code patches to implement or fix them.
There's one main leader, the "pumpking", who's in charge of releases. The pumpking usually changes between releases; currently it's Jarkko Hietaniemi. He sometimes gives other people permission to commit patches to the program. However, he doesn't have official power to control discussion, although his wishes are usually obeyed.
perl5-porters is an open group. You can e-mail the group at perl5-porters(at)perl.com or subscribe at perl5-porters-subscribe(at)perl.com.