Google acquired Nest about four years ago, but it kept the company at arm's length. Nest products are still designed and managed by Nest, an Alphabet company. That may be changing soon. Google says it's merging Nest with the Google hardware team to "supercharge" Nest's mission.
This move wouldn't have been possible in past years because Google didn't even have a unified hardware vision. Now, the company has a real team led by former Motorola CEO Rick Osterloh. It's responsible for products like the Pixel and Google Home. Bringing Nest under the same umbrella could offer better integration with Google devices and services. Google's work on machine learning in particular could help improve Nest's products, some of which already use AI to detect and recognize faces.
Google's blog post is a bit vague on how this arrangement will work. Presumably there will still be "Nest" products, but they're going to come from the same unified team that designs Google's hardware. We'll have to see how this pans out.