Only a minority of Windows users will be able to try the beta, however. IE9 will not work on Windows XP, the aged operating system that powers nearly 68 percent of all PCs running Windows. The new browser requires either Windows Vista or Windows 7.
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Thursday's announcement followed a comment made late last month by Kevin Turner, the company's chief operations officer, that the IE9 beta would show up in September. Until today, Microsoft had declined to set a date or even confirm Turner's statement.
Microsoft first announced IE9 in March, and has released four developer preview builds since then, most recently on Aug. 5 when it said the fourth such preview would be the last.
The developer previews have relied on an nearly-nonexistent interface that lacks even the most basic navigational features, such as a back button or even an address bar.
Most expect that Microsoft will debut IE9's UI (user interface) in the beta next month.
According to reports earlier this year, IE9 was to feature a look copied from Windows Phone 7's "Metro" interface. Today, Neowin.net said sources had told it that Metro is out and a "simplistic UI similar to that of Google's Chrome" is in.
If so, it wouldn't be a surprise: Other browser makers, notably second-place Mozilla, have headed in that direction, too, as they follow the lead of Google and its cleaner-composed Chrome. Mozilla's next major upgrade, Firefox 4, will feature tabs on top and will eliminate the traditional Windows menus above the browser's content area, two UI features popularized by Chrome.
IE is on a two-month upswing in usage share, according to the most recent data from metric firm Net Applications, and Microsoft has to hope that IE9 will be able to keep that momentum.
However, earlier this month Roger Capriotti, a product management lead on the IE team, refused to be drawn into a discussion of Microsoft's goals for IE9, or even whether the company thought the new browser would entice users to come back to the browser.