It's been less than a week since Apple released macOS 10.13.2 High Sierra to the masses, but it's already seeded a new beta for version 10.13.3. Oddly enough, nothing was released for iOS, watchOS, or tvOS, so we may see those later on this week.
There don't seem to be any new front-facing features coming in the update, and the release notes don't show anything that's new. There is one known issue listed for build 17D20a though, and that's that clients of NSURLSessionStreamTask using a non-secure connection will fail to connect when an error occurs during PAC file evaluation. This can happen when the file contains invalid JavaScript or the HTTP host servicing the file is unreachable.
It's not unlike macOS release notes to not say much about what's actually in the update. If Apple does indeed release a new iOS beta tomorrow, we'll likely find out more about what's coming in this cycle.
In the meantime, if you're on the macOS 10.13 developer beta, you can grab today's build by going to the Mac App Store and heading to the Updates tab.
