Today, Microsoft released Windows Server Insider Preview build 18965. Unfortunately, Microsoft still hasn't actually announced it, so there's no way to know what's new in the build.
Build 18965 RSS
Today, Microsoft released a cumulative update for those that are already testing out Windows 10 Insider Preview build 18965 on the Fast ring, bringing the build number to 18965.1005.
Microsoft has released a new Windows 10 build for Insiders in the Fast ring, and the only notable addition is a new toggle for enabling apps to be restarted when the user signs out and back in.
Microsoft today released Windows 10 Insider Preview build 18965 to the Fast ring, with some minor new features. But as always, there's a long list of fixes, improvements, and known issues.