Free wireless hotspots is a huge security and privacy threat since hackers have the tools to really make life difficult.  Check out the video below.

Connecting to a random WiFi hotspot is much like strolling into a bar in a strange part of town. Most likely you’ll have a good time, but it could ruin your day. It’s wise to assume that all hotspots harbor predators, and take appropriate precautions.
Source: http://cybercoyote.org/classes/wifi/hotspots.shtml

Laptop road warriors beware: Wi-Fi hot spots that let you hop onto the Internet anywhere you travel leave you wide open to hackers.

Source: http://www.usatoday.com/tech/wireless/2007-08-06-wifi-hot-spots_N.htm