Aviate is a free and open source (GPL) cross-platform web deployment tool that allows you to create XML-based deployment files for your web applications, so that installing, updating or upgrading web applications with all its steps would require you to only execute a deployment file.
Aviate is designed to be for the web how Makefiles are for desktop applications, or like how Apple's Automator is for automation of tasks on Mac OS X. It offers a large number of built-in commands, with more planned, and is extensible to add more commands by developers. If you have tried Capistrano, think of Aviate as an easier, more feature-rich and more generic alternative.
For example, to install WordPress, you would run the included WordPress installation deployment file. Aviate would ask you about you server's information like the address and username, and the blog information like Title and Admin e-mail. It would then go through the entire installation process unattended.
Examples for installing and upgrading WordPress:
An example deployment file for a simple web application: