We have the technology to interpret voice and natural language now. Just look at Watson on jeopardy. I don't know about you, but for a computer to come up with a question using answers is pretty impressive. If Apple uses the same programming and algorithms that Watson uses, it'll be pretty accurate I think. Iirc, Watson only missed seven questions. (But that could totally be a star I'm pulling from thin air.) Now, I know that Watson doesn't have ears but we've had diction programs for a while now. Combine the two and boom! Siri. I wouldn't exactly call it state of the art, but it's definitely innovation.