'Threaded mode' has been removed, as it is never really used. You'll probably be asking "what it is?" Don't worry, if you don't know you won't care. What it does mean is you can now go straight to the Quick Reply box at the bottom of a thread and reply more easily. You don't have to click 'Quick Reply' on a specific post now (although you still can if you want a quick way to jump to the appropriate box). Also social bookmarking links will appear on the bottom of some threads now for those that like to use those features. And finally the drop down menus are now 'attached' again to where they should be. Yay.