It's been two weeks since we last saw a full round of Developer Beta builds from Apple, so no one should be too surprised that the company released the fourth betas of iOS 10.2, macOS 10.12.2 Sierra, and watchOS 3.1.1 today. tvOS 10.1 beta 4 is notably missing, as it's one of the more major updates in this round, but Apple could always release it later today, tomorrow, or never.
Probably the biggest feature that you'll notice in iOS 10.2 and macOS 10.12.2 is support for Unicode 9 emojis. That's right, you'll finally be able to text your friends about bacon and avocados without having to worry about silly obstacles such as actual words.
The other part of the updates that is notable is the new TV app, which was announced back in October. Available in iOS 10.2 and tvOS 10.1, it aims to be a sort of hub for all of your video content consumption.
As for watchOS 3.1.1, don't expect any new front-facing features from it. As the version number indicates, it's not even a minor update.
It's a bit too early to know what's new in today's builds specifically (our test devices aren't even showing an update yet for iOS and watchOS), but we'll keep you updated if we find anything new. It's the fourth iteration, so you shouldn't expect much.
If you're not participating in the betas and are looking forward to getting these updates, they should all arrive in December.