This plugin by mdawaffe, automattic, viper007bond and nickmomrik means that each time a change is made to a post or page, those changes are emailed to the users and email addresses you specify.
Optionally, you can set what types of changes to email (post changes, page changes, attachment changes, or changes to any other ‘post type’ defined by any other plugin).
The changes are emailed as a unified diff. If the email client supports HTML emails, the diff will be colorized.
Requires WordPress Version: 2.9 or higher Compatible up to: 3.0.1
Download: http://wordpress.org/extend/plugins/email-post-changes/