Android Instant Apps
Perhaps the biggest news to Android as a whole is Instant Apps. This will be backwards compatible all the way to Android Jelly Bean too, which is huge.
With this you'll be able to use entire aspects of an app without downloading or installing it. Whether you click a link in search results, find something you want to buy from B&H or other apps. Android will temporarily install aspects of an app for use, then discard the contents when you're done. The app is never installed, and we don't have to stop what we're doing and go to the app store. Nothing. You can see a demo of this here
With instant apps you can watch video from a Ted talk, make purchases and more like you have the app installed, but you don't. It's a great feature that's still slowly rolling out as we speak.