Those waiting for Firefox 4, the upcoming latest and greatest browser from Mozilla, might not have to wait long.  Speaking at Air Mozilla today, Mike Beltzner announced that Firefox 3.7 will become 4.0.  The first alpha build of 3.7 was released on February 10.

With the switch, Mozilla will likely be much more able to meet its goal to release Firefox 4 in Q4 2010.

The biggest improvements coming in 3.7/4.0 is the Gecko 1.9.3 layout engine, which should bring improved support for new standards such as HTML5 and CSS3.  In the vision outlined in a blog post corresponding with his announcement, Beltzner says the Firefox 4 will be "Powerful: enabling new open, standard Web technologies (HTML5 and beyond!)."

He also says that the new browser will be much faster – "super-duper fast", to be precise.  The biggest speed improvement is the new JägerMonkey JavaScript engine, which speeds up repetitive scripts.  Other speed improvements include 64-bit support, a streamlined main thread, and DOM improvements.

Firefox 4.0 will bring a new look to the browser with overhauled UIs across all platforms -- Windows, Linux, and OS X.  Beltzner writes that the new layer will grant users "full control of their browser, data, and Web experience."  Among the UI improvements are an overhauled tab interface that allows hundreds of tabs to be easily managed, and allows new web app tabs.  The new UI also prompts the user with security questions earlier, so they don't have to ask as many questions later on.

A final important point to note is that with Firefox 4.0, Mozilla will be the lone player pushing a very different and truly open implementation of HTML5.  Apple and Google both support HTML5, but they both have thrown their weight behind h.264, a proprietary video codec.  Opera and Internet Explorer (sans Chrome frame) don't yet have working HTML 5 implementations that can be used with the handful of HTML5 sites out there (like the YouTube HTML 5 beta).  Microsoft's early preview build of Internet Explorer 9 uses h.264 as well.

That leaves Mozilla as the only promoter of a truly open HTML5.  Mozilla is promoting Ogg Theora, a free codec.  In fact Mozilla put up a slide presentation about Firefox 4.0 that should be available in your Firefox 3.6 browser.  The video of the slide presentation can be found here.

Beltzner gives a bit of a dig, stating, "If you have Firefox or a modern web browser that supports fully open HTML video, you can watch the presentation."

Mozilla looks to be headed in the right direction with Firefox 4.0; it should be exciting to watch the product mature through the beta phase.