I have ATT and when we visited, I had no problem on campus or anywhere between there and burlington. There were, however, a few dead spots as we headed towards Colgate. But some of this drive more than defined the term "rural" so I wasn't surprised.
I got word today that the Champlain Valley is to get 3G signal through AT&T in a few months. I cannot confirm that, but I am quite hopeful. My iPhone works great up here as it is, but it would be nice to have fast internet access off campus too.