Perl Mongers is a loose association of Perl user groups. Perl Monger groups exist world-wide -- for a full list visit the main Perl Mongers website. Australasian Perl Monger groups are (mostly) listed in the Oceania category at Perl Mongers.
Information on joining Perl Monger groups is usually included on their homepage at cityname.pm.org. In most cases you should be able to join their mailing list, or just drop in to one of the advertised meetings and introduce yourself.
If you'd like to start a Perl Monger group, please read the FAQ at pm.org. You can read up on some of the more active groups like Sydney Perl Mongers or Melbourne Perl Mongers to find out more about group activities and interests.
You can learn more about what PerlNet has to offer Perl Mongers groups at PerlNet and User Groups.
Other groups are listed on pm.org but do not appear to be active.