VT Technology Blog: Windows 10 is Official. Upcoming Windows Server Changes.

Microsoft announced a new version of Windows today at San Francisco Event, called Windows 10. Windows 10 will be a single operating system for all Windows devices, embracing Microsoft's vision of "mobile-first, cloud-first world".

Technical Preview will be available on October 1 at http://windows.microsoft.com/en-us/windows/preview-coming-soon
Consumer Preview will be available in early 2015
Windows 10 GA is scheduled to be launched around the middle of 2015.

Some of the new features:

New Start Menu
Improved task view, virtual desktops, and Alt-Tab
Improved Snap Assist and windowed apps
Search Improvements

Microsoft also shared new information about future Windows Server version (preview available on October 1)

Infrastructure upgrades: Rolling upgrades for Hyper-V clusters to the next version of Windows Server without downtime for your applications and workloads. This includes support for mixed versions as you transition your infrastructure.

Networking: New components for our software-defined networking stack that enable greater flexibility and control, including a network controller role to manage virtual and physical networks.

Storage: New synchronous storage replication that enhances availability for key applications and workloads plus storage Quality of Service to deliver minimum and maximum IOPS in environments with workloads with diverse storage requirements.

Remote Desktop: Enhanced application compatibility with OpenGL and OpenCL support.

Identity and Access Management: New scenarios to reduce the risk profile of administrators with elevated rights, including time-based access with fine-grained privileges, and new application publishing capabilities.