CMS : Drupal, Joomla, Plone and DotNetNuke

Popular Content Management Systems(CMS):

1. Drupal

2. Joomla

3. Plone

4. DotNetNuke

5. CMS Made Simple

6. dotCMS

7. ImpressCMS/MiaCMS

Ref:

Open source CMSes prove well worth the price -
http://www.infoworld.com/article/07/10/08/41TC-open-source-cms_1.html

Comparing Open Source CMSes: Joomla, Drupal and Plone -
http://www.idealware.org/articles/joomla_drupal_plone.php

Shall I choose Drupal, Joomla or Plone ? -
http://drupal.org/node/143736