In order to use QML local storage in QtQuick 2.0, the QtQuick.LocalStorage 2.0 modlue has to be imported, as described here: http://doc.qt.nokia.com/qt5-snapshot/qml-localstorage.html
That should be fine if JavaScript functions inside a .qml file use local storage.

I did however not find a way to use local storage from within .js files. Perhaps there is a way to use it from .js which should be documented, or it is simply not possible anymore in QtQuick 2.0. That would mean that we made porting from QtQuick 1.x more difficult.