Here is a summary of what I heard during Microsoft Windows 8 Keynote at Microsoft BUILD Conference:

Windows 8 could be downloaded at 8pm from http://dev.windows.com/. It will be only available in x86 32 and 64 bit editions. No activation required!

- IE 10 will feature new metro style look and feel with multi-touch supported. It is not just a new “style” of IE – it is actually part of Internet Explorer 10 core.
- New multi-screen features added to Windows 8. There could be a separate taskbar for each screen now and single background could be shared between multiple screens.
- New “Metro-style” type of applications introduced. These applications are based on HTML5/Javascript and C#/XAML. But old Win32 application will be completely supported. Any Windows 7 application will be able to run on Windows 8. Metro-type applications will occupy full screen but could be multi-tasked with other apps by occupying right or left third part of the screen. Older Windows 7 style apps will run in the same way as metro apps. They will still feature the same menus and bars they used to do.
- Windows 8 will support both ARM and X86 platforms and “Metro-style” applications will be able to run cross-platform on both platforms without any modifications.
- New interesting concept called “contracts” is introduced. For example application could make a contract with “search” part of Windows 8 to make its data searchable. Or application could share photos to Windows 8 and make them available to photo browsing interface.
Windows Explorer also got some improvements. Ribbon was introduced to Explorer user interface and new conflict solving process introduced to file-management system.
- Now you will be able to reset your Windows to get back to factory settings. If you don’t want to wipe out all the date from your application you can choose refresh option which will keep your data and preferences but wipes all underlying operating system and reinstalls it fresh.

It is still unclear when Windows 8 will be released and whether it will have different versions like Windows 7.