Use the list's mouseEventToItemRenderer() method. It's protected, so you'll have to use it from within your sub-class of list or write a public method on your sub-class to expose it. From there, if you need the item from the dataprovider for that renderer, you can use the itemRendererToIndex() method to grab the index of the item at that mouse position in your dataprovider.
If you mean the item you have clicked on, selectedItem would be it.
It you want the one you have moved the mouse over but have not clicked, have a MouseOver event handler perhaps.