Eric Butler launched a Firefox browser extension called Firesheep. The reason why Firesheep is insane is because it showcases how vulnerable it is when you are using social networking tools in public WiFi networks. Firesheep lets you log in as anyone on that public network using a simple extension. It doesn’t matter if its Facebook or Twitter. You are not very secure unless you are using HTTPS or SSL.
Zscaler Security has released a counter-measure to Firesheep called BlackSheep. BlackSheep will be able to detect whether someone is using Firesheep at a public WiFi spot.
Firesheep is able to access your logins through cookies on the network. Blacksheep tricks Firesheep with a fake login cookie and alerts the user when Firesheep is being detected. Check out the video demo below: