It makes me cringe when I hear Rush use the term immaculated of Obama. It seems such an ignorant thing to say. First, to use immaculate as a verb. Never before has anyone ever been said to be “immaculated.”
It is part of Catholic theology, however, that Mary, not Jesus, was conceived immaculately—hence her’s is said to be the Immaculate Conception. Mary’s, not the Messiah’s.
Rush gets it wrong on several levels.
However, you are quite right in noting that when the Catholic Church is referring to the dogma of the Immaculate Conception they are referring to Mary's conception. She was not divine and so the question of whether she had the stain of original sin needed to be clarified.