A new Internet Explorer 9 beta build has leaked to the web, originally reserved for close partners and TAP testers.

The build, version 9.0.8027.6000, began showing up on popular file sharing websites this weekend. The leaked version includes bug fixes, stability improvements and the latest rendering engine seen in the recent developer Platform Preview. It appears, from the digital signature, that the build was compiled as recently as November 19. Microsoft’s previous Platform Preview 7 build was labeled 9.0.8023.6000.

The new build doesn’t appear to include any UI enhancements. Microsoft has updated its download manager so that it now displays the transfer speed without the need to hover over individual downloads. The updated beta also performs better on Microsoft’s IE test drive site.

Microsoft recently released an updated platform preview build of Internet Explorer 9. Version 7 now includes 354% better JavaScript performance according to WebKit SunSpider benchmarks. In keeping with previous platform preview builds, this latest version, Platform Preview 7, does not contain the Internet Explorer 9 UI elements.

Microsoft revealed in October that the IE9 beta has clocked up over 10 million downloads. Internet Explorer 9 beta made its debut on September 15 to a fanfare of Gorillaz appearances and anticipation of Microsoft’s new look browser. The next generation browser has received a warm welcome from tech enthusiasts, developers and the media. The browser has been so popular that it grabbed 0.25% of browser market share in just two weeks.

Microsoft has targeted developers in a heavy way with Internet Explorer 9. IE 9 takes advantage of the power of the GPU for all page rendering and developers can exploit this using CSS, DHTML and javascript. A new JS engine (codenamed Chakra) is also built into Internet Explorer 9 with greater interoperability and standards support all round. Features such as rounded corner CSS support are now built in.

Microsoft has also introduced broader support for HTML5 in IE9 through its new script engine. Microsoft recently performed W3C Web Standards tests on IE9, including HTML5, SVG 1.1 2nd edition, CSS3 media queries, CSS3 borders & backgrounds, CSS3 selectors, DOM level 3 core, DOM level 3 events and DOM level 2 style. Microsoft’s IE9 is the first and only browser to deliver full hardware acceleration of all HTML5 content. Other competitors, including Mozilla and Google, are planning select hardware acceleration but at the moment Internet Explorer 9 wins hands down.

Update: Microsoft has reached out to remind users that it’s dangerous downloading leaked software. A Microsoft spokesperson issued the following statement: “Microsoft has not released this Internet Explorer 9 code to the public and we want to caution consumers and businesses that downloading software (including workarounds) from a non-genuine source can pose risks to their environment.”