Yesterday, Apple made the ninth beta version of both iOS 11 and tvOS 11 available to developers. Today, the company followed up with the latest (ninth) developer beta of macOS 10.13 High Sierra.
It's quite likely that this will be the last beta version of macOS High Sierra, as the new OS is likely to ship on or around September 12 -- the day of Apple's product announcement event. However, one feature may not be available for all users at launch time, and that's the highly-anticipated Apple File System (APFS).
Recent articles note that while APFS is enabled by default on those devices like the MacBook that use solid state drives (SSDs) for storage, issues have apparently come up with the migration of HFS+ formatted hard disk drives and Fusion drives. Apple could possibly delay the ship date of macOS High Sierra, or just ensure that at least for now, HDDs and Fusion drives retain the older HFS+ file system.