From iA wiki
See also: Content management systems
Basically a SlashClone it has adopted a premise that "everything should be a node" which allows it to implement new features quite easily. You'll find modules for Drupal which do everything from currency conversion and photo galleries to mail list and CVS integration.
Drupal is the English pronunciation for the Dutch word 'druppel' which means 'drop'.
Drop.Org is its demo site.