for all of you Firefox users, i don't know if you have heard of Firesheep.

Firesheep adds a sidebar to Mozilla's Firefox browser that shows when anyone on an open network -- such as a coffee shop's Wi-Fi network -- visits an insecure site.

i have never used a free hotspot, but for those of you who uses it please be aware of this issue and do not login to critical sites while using them, and for those who uses this plugin, please do not use it to hack peoples accounts , and for those who host free hotspots please simply secure it with any kind of password and communicate it to your customers, this way sessions will be encrypted and your clients wont be hijacked.

Francois Chaer
Even if the WIFI was protected by a password, any customer can hijack a session.
Firesheep just made it public, but you could always sniff the packets on Wifi routers for sessions then use any session edit plugin in firefox and write the session and you would be logged in as another user.
the only true solution is for everyone to Use HTTPs instead of HTTP (secure your connection) to facebook, gmail, ...
thanks for the info Zeraw, i hope people take a look at this post, since we see lots of folks hanging in those cafe with their laptops and not knowing the dangers they are in

Francois