On your iPhone, you have to tap within a folder and then select an app to launch it. On your jailbroken iPhone, though, you can activate apps with a simple gesture, status bar tap or hardware button press using Activator. Users can perform these gestures from anywhere, or adjust their settings so gestures are only recognized from their home screen or lock screen. Just be careful not to assign too many gestures so you don't get confused and activate something accidentally.