The Surface Dial revealed by Microsoft last week in New York City is compatible with Surface Pro 4 and Surface Book, just not on the screen the way it works with the Surface Studio. However a firmware update could soon be changing that, according to Vice President Terry Myerson (via Engadget), and the onscreen functionality is coming to both devices early next year.
The Surface Dial is priced at $99.99 on the Microsoft Store and can already be pre-ordered. The accessory is releasing alongside the Surface Ergonomic Keyboard and the Surface Mouse, all of which will be available on November 10. The Dial is said to even work beyond Surface products with Windows 10 PCs as a side peripheral without the need for a touchscreen.
For developers, the Surface Dial can be customized on a per-app basis letting them have full control over what winding and button pressing binds to.
We haven't been given the exact date of the firmware update for Surface Pro 4 and Surface Book, aside from "early next year." It's possible that the update might coincide with the Surface Studio release which also has a similar estimated date.