Microsoft aired Windows 10 build 10586 for the fast ring Windows Insiders. If you are one of them, you can get it via Windows Update service. This build is mainly focused on bug fixes and improvements to move forward the final build of Threshold 2. As it is a developer preview build, has some known issues.
This post lists all the fixes and known issues in this build. Before installing, please go thru the lists. Windows Feedback app to report any problems that you might encounter with this build.