Hi Chris,
It seems im also having the same problem as well. When a non admin user adds a comment to any news item whether or not it was created by an admin.
Ive tried to check the permission with ad_permission_p and it returns 0.
The Permissions are as follows:
Inherited Permissions
* Registered Users, general_comments_create
* Registered Users, news_create
* The Public, news_read
* The Public, read
* me, admin
Direct Permissions
Registered Users, general_comments_create
Can other people verify this error so it can be put in bug-tracker?