In modern browsers there are two methods for comparing nodes.
var a = document.createElement('div');
var b = document.createElement('div');
b.isEqualNode(a); // true
but
b.isSameNode(a); //false
And as for IE, it's DOM elements have non-stanard attribute, uniqueID.
But I can't imagine it can be useful in this case, since yes, you actually can compare two pointers.