A Firefox developer has revealed that pre-release versions of Firefox 3.1 have been updated with a new feature. Officially called 'Private Browsing' it will be more familiar to many as the much talked about Porn Mode that caused such controversy when Microsoft announced it was being included within the forthcoming IE8 browser.

I am not at all surprised to discover that Firefox 3.1, AKA Firefox Shiretoko, is adding this functionality as one of the things that I have always liked about the Mozilla browsing experience is the control over user privacy that it provides.

Indeed, you might ask in the light of this how is the new Porn Mode any different to the existing Clear Private Data function which deletes your browsing history, cookies, cache etc after a session at the press of a button or even automatically when you close the browser itself if you have it so configured as I do?

The answer would seem to be that it provides a best of both worlds scenario where you can ensure that no trace of your private browsing session is left on the computer but without impacting upon the non-private parts of your browsing activity. By which I mean that at present it's really an all or nothing, hit it with a lump hammer type affair. Get rid of everything to maintain privacy, but lose the benefit of that historical clicktrail for retracing steps when you need it later for example.

In essence, porn mode provides a sandboxed environment (from a privacy perspective) in which to browse but only for the duration of that session. Toggle it off and you are back to normal, without having to restart the browser and flush the cache etc.

Let's hope they sort all the bugs out before it is released though.