Firefox 3.1 may only be a point release -- from 3.0 to 3.1 -- but its just-released Beta 2 version is a good indication that the final release will be a must-have upgrade for anyone using Firefox.
Beta 2 (now available from Mozilla) unveils the browser's most important new feature -- Private Browsing, which automatically deletes all traces of a browsing session. In addition, the new beta turns on a feature designed to make the browser up to 40 times faster (at least, according to Mozilla).
Browsing in private
The most important new feature in Beta 2 is the addition of Private Browsing -- the same feature that is called Incognito Mode in Chrome and InPrivate Browsing in Internet Explorer 8. All traces of your browsing session are deleted when you use Private Browsing -- your browsing history, temporary Internet files, search history, download history, Web form history and cookies. (For obvious reasons, it's popularly known as "porn mode.")
To launch a Private Browsing session, choose Tools --> Private Browsing. When you do that, you'll get a warning that Firefox is going to close all of your current tabs to launch a Private Browsing session.
Select Start Private Browsing, and from then on, the history of your session won't be kept. The only indication that you're using Private Browsing are the words Private Browsing in the title bar of your browser. To exit Private Browsing and return to your normal session, select Tools and uncheck the mark next to Private Browsing. Your previous Firefox session will be restored -- any tabs you had opened before you launched the Private Browsing session will automatically open.
When using Private Browsing, you'll need to keep in mind that the feature doesn't quite erase all the traces of the browsing session. If you add a bookmark during a Private Browsing session, for example, that bookmark stays there, even when you exit Private Browsing and start Firefox normally. The same holds true with downloads -- those stay on your hard disk. However, the download history of the session disappears.
The biggest problem with Private Browsing is that you won't be able to have a private browsing session at the same time you have a normal one, something that both Internet Explorer 8 and Chrome let you do. Let's say, for example, you're running one instance of Firefox and want to also run a Private Browsing session. If you launch a second instance of the browser, then choose Tools --> Private Browsing, Firefox will only allow the Private Browsing instance to run -- it shuts down the other instance.