"For the web to move forward and for consumers to get the most out of touch-first browsing, the Metro style browser in Windows 8 is as HTML5-only as possible, and plug-in free," said Dean Hachamovtich, who leads Microsoft's Internet Explorer team. "The experience that plug-ins provide today is not a good match with Metro style browsing and the modern HTML5 web."
MSDN blog said: "Running Metro style IE plug-in free improves battery life as well as security, reliability, and privacy for consumers."
Although not mentioned, the support of Microsoft's own Silverlight (a direct competitor to Adobe Flash) is unknown. It is possible that Silverlight support is built-in directly.
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