Google voice search also has anaphora, or backreferences to previous searches. For example voice search for "Who was the first president of the United States?"

Google voice search also has anaphora, or backreferences to previous searches. For example voice search for "Who was the first president of the United States?" then after you get the result do another voice search for "Who was his vice president?" and Google will infer you are still talking about George Washington. One step closer to conversational interfaces!