According to rumors, Windows Blue is an upgrade for Windows 8 and Windows RT. It will see improvements to the NT kernel and support for smaller and larger screens.
Windows Blue is the successor to Windows 8. It is not Windows 9; it is an updated version of Windows 8.
Windows Blue will be a free upgrade for Windows 8 and Windows RT users.
Windows Blue is expected to launch in August of this year.
There is going to be Windows Client ,Windows Phone and Windows Server Blue Release ( it will be on the same ship pace as Windows client Blue: annually, instead of once every three years).
Microsoft is working with Intel to make sure ultrabooks and hybrids that will run on Intel's next generation processor will have longer battery life with Windows Blue.
The final result should allow ultrabooks to have the performance of a PC with the power efficiency of a tablet or smartphone.
Update: Microsoft has publically acknowledged 'Blue'
Windows 8.1 Blue release date, news and rumors : http://www.techradar.com/news/software/operating-systems/windows-blue-update-to-build-on-and-improve-windows-8-1131737?src=rss&attr=all
Windows Blue: Here's What We Know So Far http://bit.ly/11HzDOM
Microsoft's Windows Blue looks to be named Windows 8.1 http://zd.net/XV30KH
Microsoft has publically acknowledged 'Blue', announces its next BUILD conference (June 26-28 in San Francisco ) - http://www.neowin.net/news/microsoft-has-publically-acknowledge-039blue039-announces-its-next-build-conference?utm_source=twitterfeed&utm_medium=twitter …
Rumor: Windows Blue will help battery life on Intel Haswell PCs? http://www.neowin.net/news/rumor-windows-blue-will-help-battery-life-on-intel-haswell-pcs?utm_source=dlvr.it&utm_medium=twitter
Blue clues: Microsoft's Windows Server Blue mentions materialize : http://www.zdnet.com/blue-clues-microsofts-windows-server-blue-mentions-materialize-7000012947/
Windows Blue: How it could reinvent Windows (or sink Windows 8) : http://www.pcworld.com/article/2017470/windows-blue-how-it-could-reinvent-windows-or-sink-windows-8.html
Microsoft looking to 'extend touch' in 'dramatic' ways for Windows Blue, leaked video reveals : http://www.theverge.com/2013/3/21/4130764/leaked-video-windows-blue-fresh-paint-improvements
"Windows Blue" Could Be Microsoft's Way To Create Cheap, 7-Inch Tablets : http://www.businessinsider.com/windows-blue-for-cheap-7-inch-tablets-2013-3?nr_email_referer=1&utm_source=Triggermail&utm_medium=email&utm_term=SAI%20Select&utm_campaign=SAI%20Select%20Weekend%202013-03-17&utm_content=emailshare
Windows 9 improvements and possible arrival discussed : http://www.product-reviews.net/2013/03/18/windows-9-improvements-and-possible-arrival-discussed/
Windows Blue Leak Reveals Snap View Side-by-Side Apps, Different Live Tile Sizes, IE 11:
New alleged Windows Blue build shows off coming interface tweaks : http://www.zdnet.com/new-alleged-windows-blue-build-shows-off-coming-interface-tweaks-7000013035/
(Virtual) Hands-On with Windows 8 “Blue” Build 9364 : http://bit.ly/Zih17K