Publish date: 1. January 0001
> The key changes since Drupal 4.5 include:
> - PHP5 support.
> - Better search usability, improved results and relevancy.
> - Personal contact forms for registered users.
> - Improved multi-site support to run multiple Drupal sites from a
> single code base.
> - Extensible RSS 2.0 syndication support for enclosures (e.g.
> podcasts) and categories.
> - Ping Ping-O-Matic, to ping all major ping services.
> - Usability improvements for permissions, block configuration,
> statistics tracking, logs, forum configuration, content
> administration, etc.