Now we know. Microsoft's president for Windows, Steven Sinofsky, today revealed a "reimagined" Windows, which boasts a very different, tile-based user interface called Metro based on Windows Phone that is touch-savvy, runs on ARM processors as well as Intel x86 chips, and will also work on traditional keyboard-and-mouse PCs.
[Updated 9/15/2011] Although Microsoft CEO Steve Ballmer said Windows 8 would support both ARM and Intel processors on Wednesday and a parade of Microsoft execs portrayed Windows 8 PCs and tablets as equal citizens, Microsoft came clean late Wednesday and said Windows 8 on ARM-based systems will not ru Windows 7-and-earlier applications. Thus, only Metro-based apps are truly cross-device in Windows 8.
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The new version, code-named Windows 8, is now in developer preview and will be available for download later today from dev.windows.com, with no release date yet set.
Sinofsky said Microsoft redesigned Windows because "things are a whole lot different now than three years ago.... Touch is a whole new dimension. Mobility is a whole new dimension.... We want Windows to respond to that." He also said Windows 8 uses just 281MB of RAM, down from 404MB in Windows 7, and that all the new capabilities are native to the core OS, not layered on top of it. That should ease development and aid performance, he said. Microsoft has said Windows 8 will not run on smartphones, which will use Windows Phone 7 instead.
Like Windows 7, Windows 8 is designed for touchscreen PCs where users gesture on their vertical monitor screens, a contrast to Apple's strategy of restricting gestures to horizontal touch surfaces such as a touchpad. (Non-touchscreen PCs use traditional pointing devices instead, as do non-touch-savvy apps.) It also runs on iPad-style tablets. Thus, Windows 8 includes APIs for mobile devices' sensors, such as accelerometer, near-field communications, and device orientation. There are also new APIs to simplify integration of Wi-Fi and 3G networking and of printing, as well as to integrate storage, setup, and sharing access via Microsoft's Windows Live cloud service.
The new Start screen is no longer just an icon launcher, but now is a series of tiles that can contain live data, application screens, communications screens, and more. When clicked or tapped, the tile opens the content or app in its own window. Apps can interact through common exchange APIs, in what Sinofsky called a "web of apps." The Windows Explorer interface had also been tweaked, such as to allow use of custom icons in the toolbar.
Windows 8 adopts several capabilities pioneered by Apple in Mac OS X, including full-screen apps, app autosave (required for Metro apps), OS-wide search, and OS-wide spell-checking. Microsoft is also working on an HTML5-savvy version of Internet Explorer. IE is the only remaining major browser that's not HTML5-savvy.