This screencast shows how to set up Rules to allow node authors to – optionally – receive e-mail notifications when comments are posted to his or her content. It covers:

• Adding a checkbox to user accounts, turning on or off comment notification
• Sending e-mails to a node author when new comments are posted
• Not sending e-mails to the author if he/she was the one writing the comment

Please note that while I didn't manage to keep this screencast below ten minutes, my sub-conscious geek instincts made the clip 13:37 long.