3.7RC1, I don't see any option to enable the new thread posting rules when editing forums.
Edit: Had to CTRL-F5 my whole ACP for some reason, got it. It's showing up under my vBSEO options group though. You might want to give it it's own header.
This mod is a life-saver for me and my classifieds forums, since I get a lot of one-post-wonders coming through dropping ads w/o reading my forum rules. Good stuff man, thanks very much.