Mozilla has let it out on their Wiki that the next version of Firefox will offer a Private Mode, in which writes to cache, history, and other traces of a user’s browsing activity are blocked. This has been considered before but was sidelined indefinitely in the run-up to the release of Firefox 3.0.
Why the sudden change? Well, certainly the recent buzz around Google Chrome and Internet Explorer 8 shipping with privacy-mode features had a lot to do with it – not to mention Apple has been offering “private browsing” features in its Safari browser for some time now.
Sourced from Mozilla to add ‘private mode’ browsing in Firefox 3.1 - TechSpot News