Some one watching where you visited!
Yes... Mozilla has been susceptible to browser-history stealing java script code. Today, Giorgio posted some cool information about the exploit. Mozilla is already working on this. This bug has been reported. Actually they have set up a web site to show the proof-of-concept. Visit www.statrpanic.com in FF,Safari or Netscape and it will tell you which websites have you been already !
But I am not sure it will work in IE or not because my IE is not responding to the website.
Clearing history of visited website makes you safe to this attack. I mean this is one way..may be there are other ways to exploit this. But I have found this effective.
Try it yourself in FF and then in IE and see the results.