And I was supposed too make a blog post about it. Luckily for me I have a great colleague Jan Ketil Skanke that did the job for me.
So if you just head over to his blogpost HERE you will learn more about the feature.
When coming too usage of this feature, it will be a big part of "Device Based Conditional Access" that will make sure that both the user and the device are verified against your AD or/and AAD before getting access to Office 365 or your on-premises applications. I am sure it will be extended to also include other partners that can use AAD for authentication over time.
Not much info about "Device Based Conditional Access" but you will find a setup guide over at MSDN HERE and Office365 HERE