Sympa, the mailing list manager written in Perl, reached version 6 last October (latest version is currently 6.0.1)
Version 5 is already far superior to most other mailing list software including the widespread GNU Mailman. Sympa also enjoys a much more active development than Mailman, which has been stuck at maintenance releases of version 2.1 for many years.
Version 6, first of all, features a brand new web interface. You take a look at it here:
The mailing daemon went through a rewrite and it now allows parallel sending of e-mail, both on a single server or with multiple servers. It's behaviour is fully customizable.
Most configuration features are now in the database and not in text files: this makes it possible to edit most parameters directly through the web interface.
Other improvements include stronger security, list cloning, translations in a variety of languages, personalized moderation of messages and improved spam handling.
The Sympa folks also created a VMWare virtual machine which allows you to bootstrap a working Sympa environment - so that you're ready to go within minutes.