28-Jan-2012: I no longer have time to work on this module and no longer use it in any projects I'm involved with. Please contact me if you're interested in maintaining it.
Comment Login adds a user login section to the standard node comment form. This allows users to log in at the same time that they post a comment, and remain logged in thereafter. This module has the effect of disallowing anonymous commenting, but still showing the form to anonymous users with the requirement that they also supply a valid account to post.
Enable the comment login functionality in the node type administration form. In the Comment fieldset, you will be able to select "No Login Form" (the standard behavior) or to embed the login form above or below the comment form elements. There will be no changes to the comment form if the user is already logged in when the form is rendered. This module therefore has no visible effect if anonymous commenting is not allowed.
Note that as with the standalone login form, the user and password fields are marked as required, so the form will not validate without something entered in these fields. It will also fail validation if the login credentials are invalid.
Although the module does not execute the login validation functions when the "Preview" button is clicked, basic validation will still throw an error on "Preview" stating that username and password are required (when, semantically, they aren't for previewing).
You may want to theme in a link to user registration.