Perhaps not a new feature but the "Mark topics in all forums as read" is now at the top left of your "My Forums" page and the "Open Roads Forum" page which is a listing of all of the forums where it was before.
Clicking on that link will unmark all of the unread icons throughout the forum. One practical use of this is to click on it before stepping away from your computer and new topics and replies since then will be marked as unread when you return.
now that I have been using it for a few days I can't imagine what it would have been without it. Now I would like a separate one for each forum as by the time I finish a second one, the first already has new posts!