I got an email from one of the two faculty that interviewed me. There was a personal anecdote from my interview / application and he said they think I'd be a good fit there. I wouldn't say everyone gets one, but it probably isn't an exclusive club. For their 17 spots, I'd guess they might send such correspondence to applicants they can see ending up in their top 40 or so, as showing interest is more likely to promote a mutual interest from eager, influenceable, first-time applicants like us. Either way, if you are interested in Rush, it's a good sign you got some feedback as opposed to none at all.