Apple Insider’s Daniel Eran Dilger reports on carrier speeds:
Bottom line: AT&T is already fastest in general, significantly faster on average, and has far more room to grow in progressively rolling out even faster speeds to existing iPhone users over the next couple years.
He topped out at 5.4Mbps on the downlink. The fastest I have observed on my AT&T 4S is 6.38Mbps down. The data collected largely shows what should already be “known” given the network technologies at play.