Mozilla has finally released Firefox 3.6.4, after weeks of testing. The new release includes the highly talked about out-of-process plugin support.

The move, aimed at increasing browser stability, moves Adobe Flash, Apple Quicktime and Microsoft Silverlight plugins into their own process. If one of these plugins crashes, the browser will no longer crash along with it. Instead users will be given the option to reload the plugin and its content.

Currently, out-of-process plugin support is only available for Windows and Linux, with Mac versions expected in the near future. Support for other plugins is said to be on its way in future Firefox releases.

This release also fixes several security issues, 4 of which are rated as critical. A full list of changes for this release can be read in the release notes.

Existing Firefox 3.6.x users will receive the update in the coming days, or it can be downloaded directly from the Firefox website.

Oprea has released Opera 10.54, fixing five security flaws, one of which is rated as extremely severe.

The upgrade is highly recommended for all Opera 10.5x users, but the flaws have already been fixed in Opera 10.6 Beta 1, so early adopters are safe.

The nature of most of these security flaws is mostly unknown, with details to be disclosed at a later date. A rather censored changelog is available.

Opera 10.53 users will automatically be upgrading in the coming days, while other users can download Opera from the Opera website.

The Google Chrome development team have been hard at work, and have just integrated portable document format (PDF) support to their browser.

The comes on the back of an integrated Flash player, which has seen improved performance and stability within the browser.

“Millions of web users rely on PDF files every day to consume a wide variety of text and media content. The traditional browser plug-in model, though powerful, presents challenges in compatibility, performance, and security. To overcome this, we’ve been working with the web community to help define a next generation browser plug-in API” wrote Marc Pawliger, Chrome Engineering Director.

Chrome Dev Channel release 6.0.437.3 now includes built in PDF support. Users can get this version by following the instructions on the Chromium website.

Opera has just released Opera 10.60 Beta 1, almost two weeks after releasing an alpha.

New in this beta is geolocation services, offline web application support, web workers, and the new WebM video support. The browser is also up to 75% faster than Opera 10.50.

A full list of changes can be read in the changelog, while the beta browser can be downloaded from the Opera Next website.

Firefox 4 nightly releases now include built-in support for WebM video, based on Google’s open VP8 codec.

WebM support is included in Windows, Mac, and Linux Firefox nightly builds. Previously, WebM had been made available by special builds that were announced with the release of the WebM format.

Firefox Programmer Chirs Pearce has posted details on his blog for users wanting to build the browser themselves.

Eager testers can download Firefox 4 Alpha from the Firefox nightlies. Firefox 4 final is expected before the end of the year.

In response to the recent release of Safari 5, Microsoft has released a video demonstrating the performance difference between the hardware acceleration found in Internet Explorer 9 and Safari 5.

“Since the release of the first Internet Explorer 9 Platform Preview at MIX back in March and the second in May, we’ve shown a lot of demos of IE9 with other browsers. Today, Apple announced and released Safari 5. We figured we would show IE9 and Safari 5 together running some of the demos from the Internet Explorer 9 Test Drive website. Watch the Frames Per Second (FPS) Counter” wrote Microsoft’s Brandon LeBlanc.

From the video it’s clear that IE9 is a long way ahead of Safari 5, with the first benchmark showing IE9 scoring an impressive 50 frames per second, while Safari 5 only manages 9.

LeBlanc also revealed that IE9 Developer Preview has been downloaded over 1,000,000 times. Rumors are also appearing suggesting we may see a beta release very soon. We will keep you updated.

Today Microsoft have released the IE Cumulative Security Update for June 2010 which is now available via Windows Update.

Available for many versions of Windows, starting at Windows 2000, and covering all versions of Internet Explorer from IE5.01, the update is highly recommended for all Windows users.

The update fixes six security vulnerabilities, with the most serious allowing remote code execution if a user visits an infected website.

Windows users with Automatic Updates turned on will receive the update in the coming days.

With the release of Safari 5 yesterday, we are already starting to see some extensions. To use these extensions however, users must first turn this ‘pre-release’ feature on.

Doing so fortunately is very easy. Navigate to the Preferences window (File->Preferences on a Mac, or Edit->Preferences on a PC), click the Advanced tab, and tick the Show Develop menu in menu bar option. Finally click the Develop menu and click Enable Extensions. You can now install extensions in Safari.

Some early stand outs include Reload Button, AdBlock for Safari, Gmail Checker, and Safari Bit.ly Shortener.

A comprehensive list of Safari extensions can be found in the Safari Extensions blog.

Google Chrome has been updated to version 5.0.375.70 fixing 11 security issues.

Nine of these are rated as a high threat level, while the remaining two are only rated as medium. More details on these threats can be read in the Google Chrome Releases blog.

The update is available for all Windows, Mac, and Linux users, and it will be pushed out automatically to these users as usual. New users can download Chrome from the Google Chrome website.

In a release that had been hinted at in late May, Apple has released Safari 5 to the world, for both Mac and Windows users.

Performance of the updated browser has seen Apple’s Nitro JavaScript engine speed increase by 30% over its predecessor. Safari 5 new DNS pre-fetching and improved caching which helps web pages load faster.

HTML5 support has also been improved, with support for over 17 new HTML5 tags and features. HTML video now supports full-screen and closed captions.

Perhaps the most impressive feature of Safari 5 is the new Safari Reader. This nifty feature removes ads and other distractions from online articles. Safari 5 automatically detects when you are reading an article, and can be activated by clicking the new reader button which will appear in the address bar.

Most pleasing to current add-on and extension users is that Safari 5 will now support user generated extensions, which are expected to launch in an online Apple gallery in the coming weeks.

Apple’s Safari 5 can be downloaded from the Safari website for both Mac and Windows.