From TechCrunch:
Developer Eric Butler has exposed the soft underbelly of the web with his new Firefox extension, Firesheep, which will let you essentially eavesdrop on any open Wi-Fi network and capture users’ cookies.
As Butler explains in his post, “As soon as anyone on the network visits an insecure website known to Firesheep, their name and photo will be displayed” in the window. All you have to do is double click on their name and open sesame, you will be able to log into that user’s site with their credentials.
Read more: Extension Lets You Hack Into Twitter, Facebook Accounts Easily.