In this FB Developer Blog entry: New APIs for Comment Replies, it says
Last week, we launched comment replies on Facebook pages and profiles with more than 10,000 followers. This allows businesses and celebrities to engage with their fans more directly. Today, we’re updating the API so developers can build tools that make it easier for brands to monitor and respond to comment replies.
When I go look at the new Comments API documentation, it says:
Some objects are able to accept threaded comments: a top level of comments on the object itself, as well as a second level of replies to any of those comments:
There is some ambiguity here. Is the new comments API only applicable to posts on pages and profiles with more than 10000 followers, or does it apply to standard news feed posts?
It's only applicable via the Graph API where is it normally on Facebook.com. So thats posts on pages with more than 10,000 followers.
You can assume there will be compatibility throughout the system, however. So all the comments on posts I have as a user will have a parent_id of 0. Attempting to perform a POST comment_id/comments will just fail if it can't be done.