macOS 10.14 Mojave launched yesterday, but Apple already started testing the next version. Developers were just given access to a pre-release beta of macOS 10.14.1.
With availability so recent, it’s not yet known what’s in the new version. That said, the most likely enhancement is the return of Group FaceTime.
Apple promised Group FaceTime would be in Mojave, but pulled the feature out in the middle of the beta-testing process. Presumably, the dev team had decided it wouldn’t be ready at the same time as the rest of macOS 10.14. But the company promised it would be back later this year.
Group FaceTime was also removed from iOS 12 pre-release versions, but it’s back in the first iOS 12.1 beta.
In addition, Apple is surely using this update to squash any bugs or security issues that turned up since the release of Mojave.
macOS 10.14.1 for devs only
macOS 10.14.1 beta 1 is only available to those who have enrolled in the Apple Developer Program. This requires paying a $99 annual fee.
A public version will almost certainly be made available soon. Possibly as easily as next week. Getting access to that will be free to anyone willing to test potentially buggy software.