^^Agree above.. I don't think they will give you any kind of leg up, but it is a courtesy that you should extend. I took a couple thank you cards with me to each of my interviews and if they don't ask that you send them via e-mail, I took a couple minutes right afterwards to write them out and hand them to the admissions office before I left my interview day. It was helpful that all of their names and our conversations were fresh in my mind so I could reference them easily as opposed to waiting a day or 2.