I found this great plug-in for [tag]Wordpress[/tag] that allows your users to subscribe to a posts comments, any reply to the post will be sent to there email automatically.
This is much easier then having to check back on the post periodically to see if anyone has made a response to your response or subscribe to the comments rss feed.
The Plugin is very easy to install - just upload two files and activate the Plug-in in the Wordpress Plug-in’s control panel.
Currently I set the default subscription to true, but you can disable it by un-checking the subscription check box when creating a comment.
I found this plug-in from a post on www.johnchow.com lot of good info about Blog design there if you are interested