Microsoft completed its round of pre-beta tests of the company’s upcoming Internet Explorer 9 by releasing the fourth and final platform preview of the software yesterday.

The next time the vendor pushes out an IE 9 update it will come in beta form. Presumably that test version of the browser will arrive at some point in the autumn, and even as early as next month if COO Kevin Turner is to be believed.

But Microsoft hasn’t pinned an exact date on the next release yet. Instead it has offered a detailed coder-happy rundown of what goodies have been injected into IE 9 so far.

Microsoft has been bigging up the IE 9 platform preview 4 - and why not - after all, it now comes with a new JavaScript engine melded into the browser, performance has been souped up and work on the browser’s hardware acceleration is done and dusted.

Redmond’s IE general manager Dean Hachamovitch said yesterday that the browser, which debuted in preview form in March this year, was close to completion.

“With IE 9, we have worked much more closely with the developer community. Developers have had an earlier (and more frequently updated) look at the platform. With that early engagement, developer feedback has had a bigger impact than before,” he said.

So far the IE 9 platform previews have been downloaded more than 2.5 million times.

“The fourth platform preview of Internet Explorer 9, available now, shows the opportunity of fully hardware-accelerated HTML5," explained Hachamovitch. "You can run new test drive samples that show modern SVG and native JavaScript integration in action.

"In March, we promised to deliver platform preview releases approximately every eight weeks. With this instalment, you will find more performance and more support for same markup."

And, if you care about this type of thing (you probably should), the latest IE 9 preview scored well on the Acid3 benchmark test.

It grabbed an impressive 95 out of a possible 100 web standards credentials. Microsoft rightly made a bit of a song and dance about that. But remember, this isn’t the final version of the browser. When it actually ships, those points could easily be stripped away. Or else Microsoft might just surprise us all*.

The full skinny on the final IE 9 preview is here and it can be downloaded here. ®

*Yes, we know.

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