There's a lot of threads comparing Joomla and Drupal to the ubiquitous Wordpress, which for me doesn't quite gell as legitimate comparison... but I haven't seen Plone mentioned too much around here, I know nothing about it myself, and wondered if anyone has used Plone and how you would compare it to Drupal and Joomla. I don't mean which is better, we'd never all agree on that, but are there similarities between the 3 and/or reasons/features of Plone that you like above those of Drupal or Joomla? Does anyone use Plone almost exclusively even, like some do Drupal or Joomla?
Another one hard to dig up is Pligg... Not much content here about Pligg. Pligg is like digg. Here's an example of what I'm talkin' about http://www.pliggme.com (not spammin' justa example)