Blue [is] the codename for the first of a number of annual...updates to Windows 8 that is expected to hit late this summer. Supposedly Blue will [also] span...Windows Phone, Windows Server, Windows RT...SkyDrive and Outlook.com.
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Blue is optimized for power efficiency. ...when sleeping an ultrabook would remain connected to Internet-based apps such as email and social networks, so it remains constantly up to date.
Please read full at:
http://blogs.computerworld.com/windows/21949/windows-blue-download-leaked-build-9364-ahoy-itbwcw