ciantic

Currently only disables (unchecks) Commenting and Ping Backs from New Page 
-form.
Aim of this project is to eventually allow defining default values of Allow 
commenting and Ping Backs for all registered Custom Post Types straight from the Settings -> Discussion.

Commenting Defaults

Currently only disables (unchecks) Commenting and Ping Backs from New Page

Artberri

There is an option in WordPress Settings->Discussion that allows forcing users to register and log in to comment in your pages or posts. This plugin extends that option individually to each page or post, allowing you to force login only in the post or pages that you want.
In the same way but in the opposite case, if you are already forcing users to login you can open the comments on any post or page.
Make sure that you use <code>get_option('comment_registration')</code> or <code>comment_form()</code> on your theme’s comments-template to make this plugin works.
Comments, questions, feature requests and bug reports are welcome: <a href="http://www.berriart.com/en/comment-privileges-by-post/" title="Comment Privileges By Post" rel="nofollow ugc">http://www.berriart.com/en/comment-privileges-by-post/</a>

Comment Privileges By Post

Allows forcing users to register and login individually on each post or page.

Commenting Defaults vs Comment Privileges By Post