Here's a nice follow-up about the iPhone/Duke network issues from Tracy Futhey, Duke’s chief information officer:

By now many of you have read news accounts around iPhones and Duke's wireless network. Some of the reports incorrectly made it sound as if our entire wireless network had collapsed. Others made it sound as if the iPhone could not work correctly on our wireless network. Still others seem to imply that Duke's network was deficient in some way because the problem had not been encountered more broadly. The reality is that a particular set of conditions made the Duke wireless network experience some minor and temporary disruptions in service. Those conditions involve our deployment of a very large Cisco-based wireless network that supports multiple network protocols.

Cisco worked closely with Duke and Apple to identify the source of this problem, which was caused by a Cisco-based network issue. Cisco has provided a fix that has been applied to Duke's network and there have been no recurrences of the problem since. We are working diligently to fully characterize the issue and will have additional information as soon as possible.  Earlier reports that this was a problem with the iPhone in particular have proved to be inaccurate.

Originally posted here: Update on Duke's wireless network and Apple's iPhones