Along with iOS 11.1 developer beta 2, Apple released watchOS 4.1 developer beta 2 on Monday.
watchOS 4.1 adds Apple Music and Radio streaming over LTE and Wi-Fi, and presumably the beta 2 release adds support for the new Unicode 10 emoji added to iOS 11.1 developer beta 2. The update is available only to members of Apple’s developer program—there is no public beta for watchOS.
If you’re testing watchOS developer betas you can instal the update by launching the Watch app on your iPhone, then go to My Watch > General > Software Update after you install iOS 11.1 developer beta 2.