When querying the rotator for the current item outside a clientside event handler the get_currentItem() returns the DOM element instead of a RadRotatorItem object.

var rotator = <%# radRotator1.ClientID %>.control;
var currentItem = rotator.get_currentItem();

This only gets a reference to the current listitem (LI)

var currentItem = rotator.get_currentItem().control;
var currentItem = rotator.get_currentItem()._item;

These do get references to the RadRotatorItem object