The first big blow to Flash was Apple's iOS. Now Adobe Systems' browser plug-in faces another major threat to its relevance: Microsoft has banned it and all other plug-ins from the "Metro" version of Internet Explorer 10.

Metro is the modern "touch-first" interface that plays a starring role in the radically new look of Windows 8, which Microsoft plans to release in 2012. Microsoft will ship the new OS with two versions of IE10, one for Metro and one a brushed-up version of the current Windows 7 interface. While the legacy version of IE10 will accommodate plug-ins, the Metro won't, IE team leader Dean Hachamovitch said in a blog post last night during the company's Build conference.

His words should be music to the ears of those who are critical of Flash and those who are fans of a new swath of Web standards often designed to replace Flash. Dean wrote:

Running Metro-style IE plug-in free improves battery life as well as security, reliability, and privacy for consumers. Plug-ins were important early on in the Web's history. But the Web has come a long way since then with HTML5. Providing compatibility with legacy plug-in technologies would detract from, rather than improve, the consumer experience of browsi... [Read more]

Microsoft just declared that browser plug-ins' best days are behind them, but Adobe is working hard to disprove the notion with its Flash Player.

Flash, the most widely used browser plug-in, will be barred from the new "Metro" version of Internet Explorer 10 that will ship with Windows 8, IE team leader Dean Hachamovitch announced last night during the company's Build conference. In response, Adobe pointed out that Flash will still work with the more traditional "desktop" interface--but also that the company has other plans for staying relevant.

"If you look a year out, there will be important differences between what you can do in a pure HTML world vs. what you can do in Flash," Danny Winokur, vice president of the Flash runtime, said in an interview today. "Windows desktop is going to remain a fundamentally important part of Windows. By the same token, Flash will remain an important part of Web experiences for years to come."

In addition, Winokur announced that Adobe has been working on the version of Flash for Windows 8 running on ARM processors--the low-power chips that dominate the smartphone and tablet world. Those Windows 8 machines will include the ability to run IE10 in desktop mode. And when people using the Metro IE10 browser encounter a Flash Web site, they can seamlessly switch over to the desktop IE10 to proceed.