I'm with ww. Here are the advantages of Drupal for community groups:

1. broad selection of other community groups who use it and who may have already invented wheels your group needs

2. easy to turn over management of parts of the site to community members and keep other parts under your control

3. easy to plug in many many existing modules or ones you write either in PHP, or if you prefer, in Perl (with a minimal PHP glue to attach the Perl to Drupal)

There are many technically better solutions to get #3, and a few which do #2 as well as Drupal but if there's something else that has the extent of #1 that Drupal has, I would like to hear about it.

update : Actually, you could use Perl plugins without even the PHP glue ... e.g. you have a Perl Catalyst / Mason / Whatever server and simply make AJAX calls to it from Drupal.