As usual, Microsoft released a new build of Windows 10 to insiders in the Dev channel today, bringing the build number up to 20152. To go along with it, build 20152 of Windows Server is also available today for Insiders, following the same pattern we've been seeing in recent releases.
This build, just like last week's build 20150, is from the new Iron development branch, which means it's part of next year's feature update, known as 21H1. On Windows 10, some new features started to pop up last week, but Windows Server builds haven't come with a changelog since build 19551 in January, so there's no telling what's new in each build. It's likely that this week's release is as uneventful as the one for Windows 10, though.
Regardless, if you're interested in trying it out, you can head to the Windows Server Insider downloads page to get the latest build, along with matching builds of the Language packs and Windows Server Core App Compatibility Feature-on-Demand.
There are no new builds of the Windows 10 SDK this week, and it's still stuck on pre-Iron builds. However, those testing Windows 10 on ARM64 devices do have a new VHDX to download this week, with the same build number as everyone else.