It's only been just over a week since Apple released iOS 11, watchOS 4, and tvOS 11, and two days since macOS High Sierra was made available. Naturally, that means that the next minor updates are available in their beta forms, including iOS 11.1, macOS 10.13.1 High Sierra, watchOS 4, and tvOS 11.1.
Yesterday, Apple offered up iOS 11.0.1 to everyone, fixing some issues with Exchange and Outlook. You might have noticed though that if you have the beta profile installed, the update was never offered to you. It would seem that this is why, since you're getting 11.1 today.
Apple didn't offer a changelog for the updates, but it's fair to assume that they include the Messages on iCloud feature, which was removed in the earlier iOS 11 betas with a promise to come back later. There's also nothing in the macOS 10.13.1 release notes about APFS limitations for HDD-only Macs.
If you're on Apple's Public Beta Program, you'll likely see these updates within the next couple of days. Until then, it's only for developers.