Mozilla pushed Firefox 6 out the door today, updating the vast majority of its users to the browser's latest stable build.

Firefox 6 is available to download for Windows, Mac, Linux, and Android. This is the second stable version of the browser to arrive under the new rapid-release cycle, which promises a new stable build of Firefox every 6 weeks. As such, the changes to the browser are smaller in nature, and are more likely to be about stability and security concerns. However, Mozilla has taken the opportunity of this second stable rapid release to also address complaints from fans who want version numbers "to mean something," to summarize the tone and gist of many CNET readers.

Firefox users aren't the only ones with concerns. Competitors, such as Opera, have a vested interest in opposing the rapid-release cycle, which puts the browser in the news cycle far more often than before. "Web developers and IT administrators have expressed concern about the pace of new browser releases from Chrome and Firefox. We believe in a more balanced pace," said Jan Standal, vice president of desktop products for Opera Software.

While Mozilla did not address the complaints directly, it did release two new infographics detailing how the rapid-release cycle works. (Both are in QuickTime TIFF format and are reproduced here.) It also made several statements focusing on the future of Firefox.

"The next generation of innovation on the Web will be anchored by a browser that is an honest broker committed to the interests of the individual user and developer, providing amazing experiences that match those offered by proprietary platforms; and user control and developer reach and freedom that is superior to proprietary platforms. As Firefox has transformed the browser landscape before, it must do so again," wrote Jay Sullivan, vice president of products for Mozilla.

Whether Mozilla can do that is another story. Almost certainly, the company's recent announcement about making a Firefox-based mobile operating system will play a huge role in its attempts. "There's no reason why 'apps' can't incorporate the characteristics that are important about the Web. They don't today because Apple didn't build them that way. There's no reason Apple should; Apple has a different view of the world. But we can," said Mitchell Baker, chairman of the Mozilla Foundation.

As for the browser that was released today, Firefox 6 for desktops and laptops contains a number of important stability fixes, as well as some feature improvements, most of which are aimed at developers. There's a new Web Developer menu in Firefox 6, which collates tools for building and debugging Web sites into one location. These include the new Scratchpad tool, which browsers like Opera and Chrome have had for some time. It allows developers to test JavaScript before implementing it. The Web console feature also has a new auto-complete option and can have its location customized.

The browser's visual tab-grouping feature that was introduced in Firefox 4 now only loads the active tab group. Mozilla said in the blog post announcing Firefox 6 that this will cut down on overall browser load times. The "identity block," the colored left-most section of the URL, has been given a refresh to better call out the Web site you're on, and the URL bar itself now changes the text color of the URL you're on so that the domain is black, for easy identification, while the rest of the URL is gray. This is a small security change, and one that's been previously available to people who are comfortable changing their about:config, but it's definitely a strong visual cue that helps you avoid getting spoofed. Several security bugs labeled "critical" have also been fixed, repairing holes related to memory management, heap overflows, and unsigned scripts.

HTML5 also gets some love in Firefox 6, with improvements and additional support for the new Window.matchMedia API for Web optimization, and WebSockets and server-sent APIs for building more interactive and responsive real-time Web-based apps and games.

While some minor improvements were made to desktop Firefox's memory management in this release, fans will have to wait another six weeks to see the significant gains that Mozilla programmer Nicholas Nethercote wrote about last week.

The Android version of Firefox 6 includes a new Welcome page and a new look for phones running Android 2.3 Gingerbread. The browser now supports IndexedDB for storing Web pages in a local database, enabling the Android version to work better when offline. Mozilla also says the browser will start up faster and use less memory. The first of several planned changes to support tablets have arrived in this version, too, including font and icon optimization for tablets.

Release notes for Firefox 6 for desktops can be read here, and the Firefox 6 for Android notes are here.