Aegir is built by a community of system administrators and developers who share Drupal and Wordpress deployment tools, strategies and best practices, instead of continuing to write our own little shell scripts.
Aegir allows you to deploy and manage many Drupal or Wordpress web sites, and can scale across multiple server clusters. Aegir makes it easy to install, upgrade, and backup an entire network of Drupal web sites. More Info »
Once Aegir is installed, you can setup a Drupal or Wordpress web site in just a few clicks. Aegir creates the web server's web site configuration files, the web site's database, runs the Drupal or Wordpress installation process and reloads the relevant services, all automatically.
Aegir is fully extensible, since it's built on Drupal and Drush, and supports many add-ons through contributed extensions.
In addition to the GUI, Aegir can be accessed via the command line or an API, which enables the automation of many website-related system administration processes.
Documentation at http://docs.aegirproject.org