The second beta of macOS High Sierra has now been seeded to developers. We find this update two weeks after the initial seed. We’re unsure what’s new in this beta specifically, but in this version we find some improvements to the Photos, Safari, and Mail app. There’s also a few minor changes such as the file system.
To get this version developers can go to the Mac App Store and find it under updates. If you’re not on the beta yet you can get the installer from the developer center.