The new version of Android is just "M" for now, of course, and is coming out in via a Developer Preview at first. Android M is all about "product excellence" that lands in six main categories, including a few smart features but also cleaning up code and squashing bugs.
The first big feature is selective app permissions, which lets you pick and choose which permissions you let an app have. You no longer grant permissions when you install the app, and instead grant them when the app tries to perform an action that requires additional permissions.
The developer preview will see monthly(ish) updates through the fall.
Another large bit of Android M is the new payment initiative, Android Pay. It's all about simplicity, security and choice — you unlock your phone, place it on an NFC terminal, and you've just paid. When you sign up for Android Pay your account hands over a unique number for each transaction, so your main card number remains safe. Android Pay is also available inside of other apps that integrate with the service, including banks and merchants.
Going hand-in-hand with the new payment system, Android M is also integrating with fingerprint sensors at the system level. That means you'll be able to unlock your device, make Play Store purchases and authenticate payments through Android Pay all with your fingerprint if your device has a sensor.
Hoping to target some of the battery life woes of Android devices, Android M also includes new power features. Phones and tablets running M will now use a new feature called "Doze" to drop into a lower-power state as often as possible to save power, while also keeping awake for high-priority messages and notifications. Google says that a Nexus 9 running on M can get almost twice the battery life as one running Lollipop.
There's also a new Google Chrome experience, which lets individual tabs better integrate with the apps that they're associated to. For example an app can push you out into Chrome into a "custom tab," where you can access saved data that you only have in Chrome.
Android M also includes app-to-app linking, which will let apps hand off data between each other much in the same way that you can follow links between websites.
The Android M Developer Preview is coming for the Nexus 5, 6, 9 and Player, and it will launch in full capacity in Q3 of this year.