Not only are they back, but they're better than ever. Quay allows you to set the way the menu is sorted, the size of the icons on that menu, and the look of the Dock icon. Another thing worth noting is that 'Quay folders' appear on the right side of the Dock separator, as they should, and Quay itself doesn't have to be running in order for these 'Quay Menus' to work.
The developer notes that no undocumented APIs are used, and the Dock isn't hacked in anyway. Quay costs €7, and there is no free trial (if you want more than one Quay folder though, you have to pony up the cash).