I'm faced with a situation where we need to keep track of which node revision a comment was made for, so that we can display whether the comment was made for a newer/older revision, or for the one currently being looked at. Do any comment modules allow this in D7?
Not the actual use case, but a decent, easy-to-follow approximation of the idea: imagine a bookstore, where users can post comments about books. Typically, when a user asks to see a book's page, he sees the page about the book's newest edition, but in some cases a page for an older edition of the book is presented. In the list of comments for the book, comments are annotated with whether they were made about a different edition than the one being currently looked at, since the comment might not be applicable for other editions.
The actual use case is: teacher A creates learning material LM.v1 and then revises it to LM.v2; teacher B starts using LM.v2 with her class; when A revises LM.v2 to LM.v3, we still need to allow B and her class to use LM.v2, because LM.v3 might not work for B's needs at all (and changing a learning material mid-project is a big no-no); so, when looking at LM.v2, we want to be able to see all comments made about it, but with an annotation if the comment was about LM.v1 or LM.v3, since these may or may not be applicable in the LM.v2 case.