Disclaimer: all ranks mentioned here are from US News, 2014 edition.
I applied to a sizeable number of small-ish departments and I applied perhaps too broadly for my own good. Managed to get 2 acceptances and 2 waitlists from schools ranked #20-55 (not sure about UPenn or Columbia, they are painfully slow to process the remaining applications) but rejected from the low-tier programs (Tufts, Dartmouth) outright.
I understand that top-10 schools (and Michigan as well, and likely will UPenn and Columbia) reject hundreds of students that would otherwise be able to succeed once there, and, for this reason, I am not bitter about my top-10 rejections at all.
That said, I may also think that it's because I didn't publish, the professors I was interested in did not have the funding or otherwise the ability to take a student next year that I got rejected. The small size of Tufts and Dartmouth didn't help either. But, for some reason, I can't shake the feeling that their estimate of the likelihood of attendance has hurt me.
Finally, I think that, while departments may talk to each other regarding admissions, they primarily do so through their research collaborations.
#54 Notre Dame
#36 Carnegie Mellon