The long awaited Firefox 4 will hopefully be released today, with plenty of [new features][1] and support for HTML 5, CSS 3. I’m really hoping they haven’t rushed out the release to match the recent IE9 release, but the release candidate has been around for a while so lets hope that isn’t the case. I’ve been finding Firefox extremely slow for the last few months so I am glad to see they are bigging-up the performance improvements in this latest version.

As a developer, I am really keen to start looking at some of the clever bits from HTML5 and associated specs. As usual it will be the Internet Explorer take-up that really controls how soon I can start building real apps using more than small enhancements though.

Here is a summary of some of the new stuff…

New Tab Location

Tabs are given top visual priority for more efficient and intuitive browsing.

Switch to Tab

Navigate more easily by switching to open tabs from your Awesome Bar.

Firefox Button

All your menu items are in a single button for easy access and reduced clutter.

App Tabs

Take sites you always keep open—like Web mail—off your tab bar and give them a permanent home in your browser.

Stay in Sync

Synchronize your settings, passwords, bookmarks, history, open tabs and other customizations across multiple devices so you can take Firefox with you wherever you go.

Organize Your Tabs

Reclaim your browser from tab clutter! Drag and drop your tabs into manageable groups that you can organize, name and arrange in a fun and visual way.

Manage Your Add-ons

An easier way to manage your add-ons and discover new options for personalizing your browsing.

Fasten your Seatbelts

Firefox 4 contains huge performance enhancements, including our brand new JägerMonkey JavaScript engine. From faster start up times and graphics rendering to improved page load speed, you’ll notice the difference instantly.

WebM and HD Video

As pioneers of HTML5 video standards, Firefox also supports the WebM format so you can watch open HD quality video.

Protecting Your Privacy

Firefox puts your privacy first, fixing flaws in some web standards that allow bad guys to snoop around and expose your browser history.

New JS values

Changes to the C++ representation of JavaScript values allow Firefox to execute heavy, numeric code more efficiently, resulting in cleaner graphics and a better browsing experience.

Multi-touch Support

Firefox now integrates multi-touch support for Windows 7, enabling you to interact with your browser in a whole new way.

3D on the Web

WebGL brings 3D graphics to Firefox, opening the door for developers to create vivid games and new kinds of visualizations and experiences for the Web.

Audio API

Firefox is changing the way media is integrated on the web: exposing the raw audio data housed within the

Retained layers

Experience super fast scrolling on complex web pages. Simply awesome.

XPCOM

Firefox starts up even faster thanks to XPCOM module improvements that pave the way to a better extensions framework.

Stylin” Pages with CSS3

Support for new CSS3 features like Transitions and Transformations makes it easy to add elegant animations to Web pages. Learn more

Fabulous Fonts

Firefox 4”s OpenType font features gives designers and developers more control over a variety of font features—like kerning or ligatures—to create gorgeous websites.

Upgrading Forms

Firefox integrated Form features like list attributes and HTML5 validation provide the tools to make annoying form implementation development a thing of the past.

HTML5 Support

A new HTML5 parser and full support for web video, audio, drag & drop, and file handling means Firefox 4 is ready to run the best web apps of both today and tomorrow.

Web Console

With this experimental analysis tool for modern sites, Firefox allows you to peek under the hood of dynamic web pages.

JetPack SDK (Making Add-on Development Easier)

Add-ons can be installed without restarting the browser, and can be developed more easily using the new JetPack SDK and js-ctypes.

Full Hardware Acceleration

Experience super-fast graphics acceleration with Direct2D and Direct3D on Windows, XRender on Linux and OpenGL on Mac, now enabled by default, on all supported hardware.

SVG as Images

SVG files can now be used as images and backgrounds in Firefox, meaning that developers and designers can have stunning, performance-conscious websites with lighter, resolution-independent image files.

Compartments

Firefox can now better manage JavaScript objects with Compartments, offering improved cache utilization and garbage collection mechanisms for better security, memory management and overall performance.

Crash Protection

Firefox provides uninterrupted browsing for Windows, Linux, and now Mac when there is a crash in the Adobe Flash, Apple Quicktime or Microsoft Silverlight plugins. If one of these commonly-used plugins crashes or freezes, it won”t affect the rest of Firefox. Instead, you can simply reload the page to restart the plugin and try again. Learn more about plugins.

HSTS

Sites can now keep attackers from intercepting sensitive data while accessing the site by telling Firefox to automatically establish secure connections to their servers (https).

[1]: http://www.mozilla.org/en-US/firefox/features/