OS X Wireless Airport Breakage?

Yesterday I spent some quality time in the Minneapolis and Denver airports. Both advertised wireless (Centrino bannerware in Denver), and in both my Mac could see the network. The way it usually works is you point your browser at any website and the wireless service jumps in front and says something like “$6.95/day, please” and you decide whether you want to sign up. In both airports, though, when I did this the browser said it couldn’t find the site (i.e. DNS failure) and gave up. I tried pointing the DNS at a well-known DNS server’s IP address, and that didn’t help. There were people with Windows boxes around apparently getting on the air. Same story with Safari, Mozilla and IE. Bill, who was traveling with me and also has a Mac, had the exact same experience. Anyone know what’s going on?