Many thought it would be later in the year for the holiday season, but apparently Microsoft is confident that Windows 10 will be ready for a summer release.
"We continue to make great development progress and shared today that Windows 10 will be available this summer in 190 countries and 111 languages. Windows has always been global with more than 1.5 billion users around the world and here in China hundreds of millions of PCs operate Windows today. That’s why it was particularly fun to show our latest global innovation, Windows Hello, on stage for the first time, and to feature a number of Windows 10 customizations for the China market, such as Cortana in Mandarin."
More at Blogging Windows: http://blogs.windows.com/bloggingwindows/2015/03/17/windows-10-launching-this-summer-in-190-countries-and-111-languages/