Microsoft has released Windows 10 Mobile build 10586.338



From Windows Central:

At the moment, it's unclear what is new in this build, but it likely contains a number of bug fixes, tweaks and performance improvements. If you happen to notice anything astoundingly new that we've missed, be sure to let us know in the comments below. Otherwise, you should be able to start pulling the update by checking in your phone's Settings menu.

As for those of you who aren't participating in the Windows Insider program, this build's appearance on the Release Preview Ring likely means it will roll out more widely after some initial testing and feedback.

  Windows 10 Mobile build 10586.338 now hitting Insider Release Preview Ring