the feature is still there. make sure your system is fully updated and rebooted. when you point at a folder shortcut on the desktop, it gets highlighted and you see two pluses on the left side of the icon. the top plus is to select it, the botom plus, when you click on it, opens the folder contents preview with files/folders inside. it seems they made the feature non automatic, which is sort of OK. if you accidentaly pointed at a folder icon on the desktop it would always bring up the folder preview even if you didn't want it, which can be a bit irritating.
