Firesheep is creating quite a noise in the internet. It has suddenly provided a loophole to all the hackers who can now hack into your social media sites such as Facebook.
Firesheep – An addon of Firefox created by Eric Butler allows broadcasting of your cookies over the Wi-Fi network. Whenever you log on to any site, a cookie is created to keep your session open. This cookie holds login credentials of your site. Firesheep takes this cookie and broadcast this over your Wi-Fi network allowing any hacker who is using your Wi-Fi network to track down your login details.
This problem can be solved by using various addons available for various browsers which make HTTPS necessary to access the site. HTTPS is basically transferring encrypted information over the internet. Some of the addons are Force-TLS for Firefox and Chrome, HTTPS Everywhere for Firefox, KB SSL Enforcer for Chrome.