Mozilla has just passed a massive milestone, with its two billionth Firefox add-on being downloaded from its Add-ons for Firefox website.

“When we reached 1 billion Firefox Add-on downloads in November 2008, we thought it would take us less than 3 years to get to the next billion, and with your help, we’ve gotten to 2 billion in half that time! With more than 150 million add-ons in use every day, we know that the next billion add-on downloads will be here before we know it” wrote Julie Shin Choi, on behalf of the Firefox Add-ons Team.

Mozilla’s implementation of add-ons for Firefox is by far the best solution, giving add-on developers much more control and freedom compared to add-ons and extensions available for Chrome and Opera. This implementation is the key to why Firefox has so many users today.

Any Firefox users who are not using add-ons are really missing out, with add-ons available for just about everything you can think of, from download management, to social and communication, and even to web development.

Firefox add-ons are free, and are checked by Mozilla before they are released to the public. You can start browsing for add-ons on the Add-ons for Firefox website.

Just a day after it’s final release candidate, Opera has released Opera 10.60 final to the public, for Windows, Mac and Linux users.

Opera’s benchmarks show that Opera 10.60 is up to 50% faster than Opera 10.50, and is again faster than Google Chrome 5 builds. With these results, Opera is again claiming to be the worlds fastest web browser.

New in Opera 10.60 is Geolocation, HTML5 AppCache for Offline Applications, HTML5 WebM video support, web workers, and some vendor specific CSS3 styles (which are yet to be ratified by the WC3 organisation). A full list of changes can be found in the changelog.

Opera 10.60 can be downloaded from the Opera website.

Build 1 of Firefox 4 Beta 1 has just appeared on the Mozilla FTP server, with build 2 expected today also.

No change log has yet been released, and Mozilla will not announce the release until a final Beta release is ready. There are currently two bugs blocking build 2, which are expected to be fixed shortly. Currently the release is available for Windows, Mac, and Linux, with native 64-bit builds for Mac and Linux users.

Would-be-testers are warned that while more stable than the alpha releases, this build still has a lot of work to be done before it is ready to be used by the masses. As a result, some of your plugins may not work with this release.

More information on Firefox Beta 1’s release can be seen on the MozillaWiki. Firefox 4 Beta 1 Build 1 can be downloaded from the Mozilla FTP server.

Opera is continuing with its fast pace of development, releasing Opera 10.60 RC2, just a day after releasing RC1.

Not much has changed in this release, with only a few bugs having been fixed since the first release candidate. A full list of changes can be seen in the changelog.

With the current pace of development, Opera 10.60 final is no doubt expected within the next week.

Opera 10.60 RC2 is available for Windows, Mac, and Linux users, and can be downloaded from the Opera Desktop Team’s blog.

The Google Chrome team are in the process of implementing some changes to the user interface, in the aim of streamlining the toolbar.

Changes include displaying either a magnifying glass, or a globe icon in the URL bar to help determine what the browser is doing with the user input. Secure sites will now display the padlock icon at the start of the URL, rather than at the end of the URL bar.

Reasons for the changes, and a list of other planed changes can be seen on the Chromium blog.

These changes are starting to make their way into Chrome Dev Builds.

Early builds of Firefox 4 are starting to show the browser new interface.

Part of the revamp includes moving tabs above the address bar by default, which isn’t something everyone is happy about. Thankfully, this can be changed easily by the user.

“This is a preference that users can change by right clicking on any of their toolbars.  Moving the default tab position is obviously a significant and to some extent controversial change to the Firefox UI, which is why we made the video above to help explain our rationale” explains Alex Faaborg, User Experience Design at Mozilla.

Firefox 4 Beta’s are expected in the next few weeks, with a final release before the end of 2010.

Google has just released Google Chrome 5.0.375.86, fixing 5 new security vulnerabilities, 3 of which are rated as high, and the other two are rated medium.

As a result of this fix, the integrated Flash player is now enabled by default.

Full details on the security vulnerabilities can be read in the Google Chrome Releases blog.

The update will be pushed out to current Stable Channel Chrome users, or new users can download the browser directly from the Google Chrome website.

Just days after the release of Firefox 3.6.4, Mozilla have pushed out Firefox 3.6.6. The update fixes 1 bug, but why Mozilla skipped version 3.6.5 is unknown.

“Firefox 3.6.6 modifies the crash protection feature to increase the amount of time that plugins are allowed to be non-responsive before being terminated” said the Firefox 3.6.6 release notes.

Existing Firefox 3.6.4 users will receive the update in the coming days, or it can be downloaded manually from the Firefox website. The update is available for Windows, Mac and Linux users.

Seven weeks after their last release, Microsoft have let Internet Explorer 9 Platform Preview 3 out of the bag.

The updated preview release includes support for the HTML5 video tag, canvas tag support and embedded fonts using the WOFF standard.

“The third Platform Preview of Internet Explorer 9, available now, continues the deep work around hardware acceleration to enable the same standards-based markup to run faster. This is the latest instalment of the rhythm we started in March, delivering platform preview releases approximately every eight weeks and listening to developers. You’ll see more performance, same markup, and hardware accelerated HTML5″ wrote Dean Hachamovitch
General Manager, Internet Explorer.

This latest release performs well in benchmarks, now scoring 83/100 in the Acid3 test, up from 68/100 in the last platform preview. SunSpider testing shows the browser is almost on par with the recently released Safari 5, which our own testing confirmed.

Willing testers can check out the IE9 Platform Preview release from the Test Drive IE website.

Google have today announced the launched a new website, called HTML5 Rocks, showcasing the power of HTML5 and related technologies.

The site currently includes nine tutorials demonstrating how to utilise some of HTML5’s new features, along with an in-depth HTML5 powered presentation on the new language.

“Because HTML5 and its related technologies cover so much ground, it can be a real a challenge to get up to speed on them. That’s why today we’re sharing HTML5 Rocks, a great new resource for developers and teams looking to put HTML5 to use today, including more information on specific features and when to use them in your apps” wrote Paul Irish, Google Chrome Developer Relations.

I encourage developers to dive in and check it out. An all HTML5 web is sure to see some interesting sites and applications.