AirDefense monitored the air at Wi-Fi Planet and found a huge number of security breaches: The company saw 21 attempted man-in-the-middle attacks, of which 16 were successful. The rest of the numbers are pretty shocking. In just one day, AirDefense also found 75 denial-of-service attacks targeted at APs, 125 attempted identity thefts by spoofing MAC addresses and 24 fake AP attacks.
With that kind of activity, you'd better use the best security options you've got. But most people didn't. Only 6 percent of corporate email downloads used a VPN and 89 laptops were configured to allow ad hoc networking. I think this kind of data is an argument for not using Wi-Fi in an environment like Wi-Fi Planet unless you know how to secure your laptop.