Mozilla updated Firefox 4 today to release candidate status, meaning that the features are locked, and barring the discovery of any major bugs, this version is likely to become the browser's official release. Available to download for Windows, Mac, and Linux, Firefox 4 release candidate 1 contains no major bug fixes, and instead offers a series of stability, compatibility, and performance tweaks.

Mozilla's Web o' Wonder notifies you at the top of the page if your graphics card drivers are out of date, an essential upgrade to perform to take advantage of hardware accelerated browsing. (Credit: Screenshot by Seth Rosenblatt)

Longtime Firefox 4 beta watchers will notice a squaring off of the browser's tabs, and for those who missed it in the last beta, the browser will now automatically pin itself to your Windows 7 taskbar if the default browser option is checked off during installation. Mozilla has also put together a series of "future-Web" demos at the company's "Web o' Wonder" site, which actually has at least one legitimate use: it warns you when your hardware drivers are out of date, an essential update for taking advantage of the hardware acceleration that most major browsers are developing to speed up Web browsing. Not updating graphics card drivers can end in any hardware accelerated browser crashing.

One concern with Firefox pushing a major update is that add-on developers must update their older add-ons to work with the new browser. Instead of waiting for developers, though, Mozilla recommends that you install the Add-On Compatibility Reporter to ensure that the developers of your favorite add-ons get notified if their code is broken for Firefox 4.