When a reply is made to a comment, a twitter notification (@twittername) will be sent to the original comment author to notify him/her of the reply. T
In this version all commenters will receive the notification. In the next version it will be possible to check a checkbox to get the notification.
You need a twitter account to make this plugin work because the plugin needs a place to send the notifications from. If you don't want to clutter your twitteraccount with these replies, make a new twitter account specifically for this purpose.