Update (2/10): Instant Tethering is now rolling out to the Pixel, Pixel XL, Nexus 6, Nexus 5X, and Nexus 6P. As long as they are running Android 7.1.1, they’ll be able to host and share their internet connections automatically with other supported device signed into the same Google account.
Original (1/20): A new and previously unannounced feature is starting to roll out today as part of a server-side update to Google Play Services. The new feature is called Instant Tethering, and it is supposed to make it easier to connect to a device with a mobile hotspot.
Online reports say this feature is part of Google Play Services 10.2. Basically, if you own more than one Android device that shares one Google account, Instant Tethering will allow one of those products to find any of those others that also have a cellular data connection, so they can automatically connect to that device and share that data.
This kind of feature will likely be helpful for people on the road who own a smartphone and an Android tablet… the latter of which might not have cellular hardware. In that case, the tablet can quickly connect to the smartphone’s data connection without a lot of fuss. This feature also displays the remaining battery life on that connecting device.
While some people are reporting Instant Tethering as going live right now, it looks like Google is only beginning to roll out this feature, so it may take several days for this update to reach your devices.