Josh Hallett made an unusual discovery at Atlanta's airport: Running an RSS reader looks like hacking to the airport's pay wifi service.
If you are using the paid wifi in the terminal and you open up a desktop-based RSS reader like NetNewsWire, the network assumes your flurry of RSS-grabbing activity is a suspicious event. About 10 seconds after opening my RSS reader I was presented this message in my browser: "Anomalous Behavior Detected -- Request Blocked."
Yep, I was blacklisted. The 'system' assumed that my machine was infected with a worm or virus. In the end I was able to experience around a minute of my paid wifi service.